Rare-Earth Elements in the Swedish Alum Shale Formation: A Study of Apatites in Fetsjön, Västerbotten

Independent Project at the Department of Earth Sciences

Självständigt arbete vid Institutionen för geovetenskaper

2019: 29

Rare-Earth Elements in the Swedish Alum Shale Formation: A Study of Apatites in Fetsjön, Västerbotten

Sällsynta jordartsmetaller i Sveriges alunskiffer:

en studie av apatiter i Fetsjön, Västerbotten

Fredrik Engström

DEPARTMENT OF EARTH SCIENCES

I N S T I T U T I O N E N F Ö R G E O V E T E N S K A P E R

Independent Project at the Department of Earth Sciences

Självständigt arbete vid Institutionen för geovetenskaper

2019: 29

Rare-Earth Elements in the Swedish Alum Shale Formation: A Study of Apatites in Fetsjön, Västerbotten

Sällsynta jordartsmetaller i Sveriges alunskiffer:

en studie av apatiter i Fetsjön, Västerbotten

Fredrik Engström

Copyright © Fredrik Engström

Published at Department of Earth Sciences, Uppsala University (www.geo.uu.se),

Uppsala, 2019

Abstract

Rare-Earth Elements in the Swedish Alum Shale Formation: A Study of Apatites in Fetsjön, Västerbotten

Fredrik Engström

The Caledonian alum shales of Sweden host a vast number of economically interesting metals. In Fetsjön, Västerbotten, the shales contain significant amounts of rare-earth elements, vanadium, molybdenum and uranium. As metals with a multitude of high- technological applications, the former rare-earth elements (REEs) are particularly attractive in a world where the supply may be exhausted as the demand continuously increase while new deposits are not being discovered fast enough. Meanwhile, the latter uranium notably constitutes as an unwanted secondary product during the extraction of rare-earth elements.

As the mineral association of the REEs in Fetsjön is unknown, the intent of this study is to analyze and thus determine their mineralogical expression. The assumed REE- bearing mineral apatite was confirmed to host the rare-earths in the Fetsjön shales after microscopy and spectrometry analyses.

Keywords: apatite, rare-earth elements, uranium, alum shales, caledonides

Independent Project in Earth Science, 1GV029, 15 Credits, 2019 Supervisor: Jaroslaw Majka

Department of Earth Sciences, Uppsala University, Villavägen 16, SE-752 36 Uppsala (www.geo.uu.se)

The whole document is available at www.diva-portal.org

Sammanfattning

Sällsynta jordartsmetaller i Sveriges alunskiffer: en studie av apatiter i Fetsjön, Västerbotten

Fredrik Engström

Alunskiffern längs Sveriges Kaledoniska front innehåller ett flertal ekonomiskt attraktiva metaller. I Fetsjön, Västerbotten, består denna alunskiffer av höga halter med sällsynta jordartsmetaller, vanadin, molybden och uran. Sällsynta jordartsmetaller har ett flertal högteknologiska användningsområden och är därmed särskilt intressanta i dagsläget då tillgångarna kan sina allt eftersom den globala efterfrågan överstiger takten av att nya tillgångar hittas. Samtidigt medför uranhalten ett problem som en oönskad sekundärprodukt under utvinningen.

Då kännedomen om vilka mineral som bär på de sällsynta jordartsmetallerna är okänd så är syftet med denna studie att analysera och därmed fastställa vilka mineral de är associerade med. Mineralet apatit som antogs vara bäraren av metallerna bekräftades även att innehålla dessa efter mikroskop- och spektrometeranalyser.

Nyckelord: apatit, sällsynta jordartsmetaller, uran, alunskiffer, kaledoniderna

Självständigt arbete i geovetenskap, 1GV029, 15 hp, 2019 Handledare: Jaroslaw Majka

Institutionen för geovetenskap, Uppsala Universitet, Villavägen 16, SE-752 36 Uppsala (www.geo.uu.se)

Hela publikationen finns tillgänglig på www.diva-portal.org

Table of Contents

Introduction ... 1

Background ... 2

Geology ... 2

Fetsjön ... 3

Previous Work ... 8

Method ... 10

Results ... 12

Discussion ... 20

Recovery ... 20

Conclusion ... 20

Acknowledgements ... 21

References ... 21

1

Introduction

It is often said that rare-earth elements (REEs) ironically, are not that rare. This statement is applicable to the lighter REEs but does not apply to the heavier ones.

More importantly, REEs are very unevenly distributed throughout the world, of which the vast majority – about 90% – is extracted in China. Rare-earth elements are critical resources used for a variety of high-technological applications, and as the demand for the heavy REEs increase drastically the world may soon face a supply shortage. Thus, new deposits of REEs are needed and exploration for the resources are ongoing (Kanazawa & Kamitani 2005).

All the way from Finnmark in Norway to Skåne in Sweden, along the Scandinavian mountains, there is a thin shale formation deposited on the Baltoscandian platform.

This Alum Shale Formation is significant in that it hosts a variety of economically interesting materials. In recent times, it has garnered attention as it contains vanadium, molybdenum, nickel, copper, and uranium but more importantly – rare-earth elements.

The purpose of this study is to determine the minerals constituting the rare-earth elements in the alum shales of Fetsjön, an area currently being prospected by the company Eurobattery Minerals. Fetsjön is located in Västerbotten, 40 km northwest of the town Dorotea along the Caledonian Front. Analyses of drill core samples taken from SGU Malå will be performed using standard microscopy and spectrometry methods to confirm whether or not apatites carry the rare-earths.

The shales of Fetsjön fall into two separate lithological categories that repeat throughout the stratigraphy of Fetsjön - phosphoritic and graphitic shale. Previous geochemical analyses of the shales in Fetsjön have been carried out by Mawson Resources and show high concentrations of rare-earth elements as well as uranium, vanadium, molybdenum, nickel and copper. The rare-earth elements and uranium appear to be associated with units of phosphoritic shale while V, Mo, Ni and Cu are enriched in graphitic shale units. However, knowledge regarding the mineral association of the mentioned elements is lacking. Due to their continually increased industrial importance, REEs are of particular interest in this study and requires a mineralogical examination so that the development of Fetsjön may continue.

Furthermore, as the shales are uranium-bearing and because rare-earth elements

often are found together with uranium, it is feasible that the REEs are associated with

uranium, which would present itself as a problem due to the Swedish laws surrounding

uranium according to minerallagen (1991:45).

2

Background Geology

During the Silurian-Devonian, the continents of Avalonia, Laurentia and Baltica collided as a result of the Iapetus Ocean closing. Consequently, a large-scale mountain building era known as the Caledonian Orogeny initiated. The remnants of the orogeny can be found in the Appalachians of eastern North America, in Ireland and Scotland, in Svalbard and Greenland, as well as the Scandinavian mountains of northern Europe (Gee et al. 2010), see figure 1. It was during the Lower Paleozoic, a timeframe when the Baltoscandian platform was characterized by tectonic stability, that the alum shale formation was deposited (Andersson 1985). What follows is a description of the geological background and setting prior that deposition.

The Scandian collisional orogeny took place in the Silurian-Devonian and led to the continent of Laurentia being underthrusted by Baltica (Gee et al. 2008). This orogen has been recognized to have been on the scale of Himalayan proportions. However, since then the mountains have undergone significant erosion (Gee et al. 2010). A distinct trait of this orogen is an array of nappes thrusts in a west to east direction, divided into a series of allochthons (figure 2). Deformation led to gentle and upright folds in the eastern part of the orogen and when going westwards, these gradually become tighter with isoclinal and recumbent elements (Gee & Sturt 1985).

Figure 1. Map illustrating the Caledonian mountain chains areas during Early Devonian

(Wikimedia Commons 2008).

3

Dominating the orogenic structure of the Caledonides are thrust-nappe structures, derived from the outer shelf of Baltica and the margins of Laurentia (Higgins et al.

2008). The nappes are consecutively grouped into three categories of a Lower, Middle, Upper and sometimes a fourth Uppermost Allochthon – a designation based on stratigraphical and structural features (Gee & Sturt 1985). The next section will describe the Autochthon in more detail as this study concerns the Alum Shale Formation found there. For a more comprehensive picture regarding the allochthons of the Scandinavian Caledonides, see Gee & Zachrisson (1979).

The Autochthon is composed of Middle-Upper Cambrian black and grey shales deposited on the undisturbed crystalline foreland of the Baltic plate. Sometimes, the additional term Parautochthon is used for units that resemble those of the autochthon but that have undergone some tectonic disturbance (Gee & Zachrisson 1979). The Pre-Caledonian basement is mainly composed of granites, gneisses, porphyries and migmatites (Gee & Sturt 1985). These mostly undeformed shales acted as the décollement that the Lower Allochthon was transported across (Gee & Sturt, 1985).

These shales are uranium-bearing (Andersson 1971) and represent the ones examined in this study. The deposition of the shales occurred in a basin that extended westwards as far as into Norway during the Middle to Upper Cambrian but may reach up till the Tremadoc in some areas. Locally, these alum shales may be up to 200 meters thick due to tectonic repetition. This is the most extensive stratigraphic group in all of Scandinavia and occurs all the way from Finnmark in the far north of Norway to Skåne in the south of Sweden (Gee & Zachrisson 1979; Gee et al. 2010), see figure 2. The alum shales are overlain by Ordovician limestones that are replaced by greywackes westwards.

Fetsjön

The stratigraphy of Tåsjön has been described in much detail by Gee (1972) and can

largely be applied to that of the nearby Fetsjön, the subject of this study. Rocks in

Tåsjön (and thus, extensively Fetsjön) can be treated as three separate

lithostratigraphic groups: a Cambrian arkose group resting on the crystalline

Precambrian basement, followed by a Varangian quartzite-shale group and a Lower

Paleozoic greywacke-shale group containing a distinct alum shale formation and a

greywacke shale group. It is this uraniferous alum shale group that is the interest of

this study. What follows is a brief description of the stratigraphy of Tåsjön.

4

Figure 2. The location of Fetsjön plotted on a map outlining the tectonostratigraphy of the Scandinavian Caledonides (Gee et al. 2010, modified).

An unconformity separates the underlying Precambrian basement primarily composed of porphyritic granites from the overlying arkose, quartzite and sandstone beds that make up the arkose group. Specifically, two arkosic sandstone beds dominate the group.

The Quartzite-Shale group begins with a tillite formation resting on top of the

previous Arkose Group. A white feldspathic quartzite follows, running into red siltstones

and later shales, overlain by another white quartzite formation. Next is a sequence of

green sand and siltstones, occasionally cross-laminated. This same sequence is

5

repeated higher up in the sequence, again separated by white quartzite. The top quartzite formation runs into a conglomeratic quartzite, laminated with green siltstones.

The uppermost lithostratigraphic group is the Greywacke-Shale Group. It is composed of two formations – a lower black alum shale unit followed by an upper greywacke-grey shale unit. The basal Cambrian black alum shale has a thickness ranging from 40 to 50 meters and contains stinkstone lenses. Sometimes, this unit may be covered by a 1 to 2 meters thick banded limestone bed. The evident variation of thickness of the unit in a north to south-eastern direction has been credited as either a result of overthrusting of the shales (Asklund 1935) or due to morphological changes in the basin where they were deposited. The Greywacke-Shale formation stretches throughout the Lower Paleozoic Swedish sequences, with a thickness that is locally preserved (Anderson et al. 1985). In the Tåsjö area it has an usually high thickness ranging from 200-300 m. The lowermost unit is a calcareous and phosphatic sand- siltstone, followed by a shale and siltstone member. This sediment is highly concentrated with uranium (Gee 1972). According to Hans Selbach, the black alum shale formation as described earlier roughly corresponds to Fetsjön’s phosphoritic and graphitic shales. Based on previous drillings and chemical analyses by Mawson Resources, a generalized lithological sequence has been constructed showing that the stratigraphy of Fetsjön is made up of cyclic units of phosphoritic and graphitic shales.

A combination of the lithological data with earlier elemental analyses of the drillcores

by Mawson Resources show a clear trend of uranium and rare earth element content

in the phosphoritic shale, while the contents of vanadium, molybdenum, nickel and

copper are present in the graphitic shale. Due to the high carbon content of the shales

in nearby areas such as Eurobattery’s license in Ormbäcken, and as noted in

Andersson (1985), it is also possible that the shales contain graphite. What follows is

a figure depicting a log of a typical borehole in Fetsjön (KRODD07045).

6

Figure 3. A typical borehole (KRODD07045) from Fetsjön illustrating the affinity of elements

with specific rock lithologies. Uranium (U) is enriched primarily within sequences of

phosphoritic shale (purple rock code) together with Total Rare-Earth Elements (TREE), while

Molybdenum (Mo) and Vanadium (V) appear concentrated within graphitic shale units (pink

rock code). Values are listed in parts per millions (ppm) but specific values have been removed

(Eurobattery Minerals).

7

Table 1. Abundance of individual and total rare-earth elements (TREE) as well as uranium in

the boreholes analyzed during this study. The abbreviations PSH and GSH specifies

phosphor- or graphitic shale. The values refer to the listed intervals (Eurobattery Minerals).

8

Previous Work

Geochemical studies of the Swedish alum shales have been done in the past. While several of these have acknowledged the presence of rare-earth elements, no consensus regarding their mineral association has since been made. Knowledge of the uranium content in the shales throughout Sweden is thorough and has been known locally since at least 1893, as reported by Nordenskiöld.

The presence of rare-earth elements in the shales has been demonstrated by Andersson (1971). This study reported unusually high concentrations of REEs in the shales of Krontorpet, 4 to 8 times higher than that of average shale composition as described in Krauskopf (1967). In particular, the contents of Y, La, Ce and Nd were the most compelling. Furthermore, the minerals quartz, glauconite, apatite, illite, calcite, siderite, dolomite, pyrite, k-feldspar and kaolin / chlorite were found using XRD and optical studies. The rare-earth minerals were not determined but XRF analysis of the apatite did confirm high Y concentrations in the samples, suggesting that the apatite could contain at least some of the REEs. Later in 1985, Andersson observed a total rare-earth element enrichment of 0.041 wt.% in the shales of Ranstad in Västergötland.

Similar to the chemistry of Fetsjön, the same study also noted the presence of V, Mo and Ni. The fact that these economically interesting elements were observed not to be enriched within the same stratigraphic units shows comparisons with that of the shales in Fetsjön.

In total, there are about 200 different rare-earth minerals (REMs) identified so far globally, associated with an array of different mineral classes. Of these, the most economically significant are the phosphate minerals monazite (Ce, La)PO 4 and xenotime YPO 4 , as well as the carbonate mineral bastnaesite (Ce, La)(CO 3 )F.

However, the more common phosphate mineral apatite may also be REE-bearing. Due to the similarities in ionic radii, REEs are often substituted by natrium, calcium, thorium and uranium in the minerals. Because of this, production of REEs often result in the undesirable accumulation of radioactive elements (Kanazawa & Kamitani 2005).

In 1957, AB Atomenergi encountered a radioactive anomaly and carried out exploration in the Tåsjö area of Västerbotten confirming the existence of uranium in the shales as well as noticeable amounts of apatite and glauconite (Gee 1972). Going back to the study by Andersson (1971), it was concluded that the uranium was primarily bound to apatite. However, autoradiographs made on the minerals also indicated that uranium content of individual apatite grains may differ significantly. Further south in the Billingen-Falbygden area of Västergötland, the uranium of the alum shales was associated with organic matter with some enrichment in phosphorite and zircon. No uranium mineral was found (Andersson 1985). The kolm lenses outlined by Nordenskiöld (1893) that appear in the alum shales supply the most uranium-rich part of the formation. Individually, these lenses can contain 2000 to 5000 ppm of uranium.

Certain areas such as Ranstad in Västergötland suggests that sedimentation rate was

a fundamental factor as the thickness of shale units exhibits an inverse relation to

uranium content (Andersson et al. 1985). Correspondingly, thicker parts of the

uraniferous unit in Garaträsksjön, near Tåsjö, contains on average 250 ppm uranium

while the less thick parts of Kvarnån contain up to 500 ppm (Gee 1972). Lecomte et

al. (2015) studied uranium mineralization of the alum shales in Sweden and how the

9

degree of metamorphism and burial affected the mineralogy. They concluded that in southern Sweden where the alum shales were not extensively buried, the uranium content appeared as biogenic phosphates. In northern Sweden the alum shales were subjected to greater metamorphism during the Caledonian orogeny as indicated by the low-grade greenschist facies and folding. Here, uranium was associated with phospho- silicates U-Si-Ca-P (±Ti ±Zr ±Y) and low amounts of uraninite. Therefore, the extent of metamorphism appears to affect the mineralogical expression of uranium. Additionally, it was found that in metamorphosed alum shales that middle rare earth elements (MREEs) were associated with uranium-bearing Apatite-(CaF[OH]) nodules.

Interest in the trace-element content of the shales started after the 1940s, and has since been investigated several times, confirming the presence of several heavy elements such as Ni, Mo, Co, Cu, Zn, U, V, As, Se, Ag, Au and platinum-group elements (PGEs) (Vine & Tourtelot 1970; Holland 1979; Wignall 1994). Similar results were derived by Andersson et al. (1985) where high concentrations of the trace elements U, V, Mo, and Ni were demonstrated in the alum shales of Jämtland. In an extensive study of the alum shales in Billingen, Västergötland by Armands (1972), similar results were then as well proven. Factor analysis showed Mo and V associations in several combinations. In the Upper Cambrian portion of the alum shales, Mo interestingly appeared together with Cu, V, U, Ni among others and organic carbon. The distribution of Mo generally coincided with that of organic carbon and increased upwards through the shale. Meanwhile, V correlated most positively to S but also to U and Ni. Thus, V (and Ni) are probably associated with some sort of sulfur complex other than pyrite (FeS 2 ) as there appeared to be a low correlation between V and iron.

Today, the alum shale formation can be seen from Finnmark in northern Norway all the way down to the southern tip of Skåne in Sweden. In fact, it can even be traced westwards below the nappes (through windows) all the way to the coastal areas of Norway, where they too are radioactive. This is accepted as evidence that the shales were deposited considerably across western Scandinavia. Generally, this alum shale sequence ranges from 10 to 60 meters in thickness but can reach up to thicknesses of 200 meters due to tectonic repetition (Andersson et al. 1985).

The precipitation of phosphates (such as apatite) could have materialized in a closed basin environment, which would have provided the suitable condition of low redox potential, as indicated by the minerals (apatite, pyrite, organic matter, glauconite and siderite) of the phosphatic glauconite siltstones (Krumbein & Garrels 1952).

Kazakov (1938) suggested that deeper currents supplied the relatively warm water,

high pH shelf environment with cold and phosphate rich water resulting in the

precipitation of phosphate.

10

Method

Thin section samples were imaged and analyzed for apatite using JEOL JXA8530F electron microprobe and later energy dispersive spectrometer to establish if apatites are REE-bearing. In total, 18 samples from 11 different boreholes with varying depths and lithologies were analyzed (table 2). The boreholes are plotted on a map of Fetsjön in figure 4. These cores were drilled by Mawson Resources Ltd and obtained from the drill core archive at SGU Malå.

Core samples were selected based on appropriate size, as well as how close they represented the overall drill core lithology. Additionally, they were classified as either phosphoritic or graphitic shale based on Eurobattery Minerals own terminology.

Samples with distinct features such as veins were avoided, as these were atypical and would misrepresent the later mineralogical studies. The samples were then sent to be made into thin sections that later were used for the microscopy and spectrometry analyses.

Table 2. Boreholes analyzed in this study with their respective sample depth and lithological classification.

Hole-ID Sample depth

m

Lithology

KRODD07028 81.5 Graphitic

KRODD07028 KRODD07028 KRODD07022 KRODD06004 KRODD06005 KRODD06005 KRODD07023 KRODD07023 KRODD07045 KRODD07045 KRODD07047 KRODD07047 KRODD07051 KRODD07050 KRODD07050 KRODD07052 KRODD07053

87.6 42.3 89.75

41.2 28.5 44.2 39.1 92.0 38.6 52.0 9.6 38.7 43.4 10.25

15.0 21.9 45.0

Phosphoritic

Graphitic

Graphitic

Phosphoritic

Graphitic

Phosphoritic

Graphitic

Phosphoritic

Graphitic

Phosphoritic

Graphitic

Phosphoritic

Phosphoritic

Graphitic

Phosphoritic

Graphitic

Phosphoritic

11

Figure 4. The location of Fetsjön (place of study) plotted on a map of the Scandinavian Caledonides (Gee et al. 2010, modified). Additionally, it shows all of the boreholes analyzed in study.

As the assumed mineral carrying the rare-earth elements, apatites were targeted

during the microscopy session and later sent for quantitative spectrometry analysis at

the Swedish Museum of Natural History using a laser ablation ion-coupled plasma

mass spectrometer, specifically a ESI NWR193 ArF eximer was the instrument of use.

12

Results

The performed analyses confirmed that the apatites are REE-bearing, of which the main concentration consists of LREEs (table 3, figures 5-16). Many of the samples – primarily those of graphitic lithology – did not contain suitable apatites and are thus lacking data. In the end, only 6 of the samples contained appropriate apatites for analysis.

Table 3. Rare-Earth Element concentrations in apatites from HR-ICP-MS. Values are normalized to the apatite standard Durango DCa.

Sample Spot Ce

ppm Dy ppm

Er ppm

Eu ppm

Gd ppm

Ho ppm

La ppm

Lu ppm

Nd ppm

Pr ppm

Sm ppm

Tb ppm

Tm ppm

Yb ppm

06004-41.2 1_1 2957 774 211 238.8 1356 116 998 8.12 3309 567 1329 177 20 78

06004-41.2 2_1 1571 649 170 202.2 1099 95 513 5.55 2618 372 1148 144 15 58

06004-41.2 2_2 1740 700 186 229.4 1208 104 563 5.93 2820 409 1251 161 17 62.4

06004-41.2 2_3 1747 646 168 197.2 1156 93 607 5.65 2522 393 1136 148 15 56.4

06004-41.2 2_4 1559 608 164 197.2 1073 90 480 5.24 2512 362 1126 141 15 53.3

06004-41.2 2_5 1739 658 177 207.1 1169 99 545 5.59 2620 390 1176 159 16 58.8

06004-41.2 2_6 1625 620 162 196 1055 90 524 5.16 2508 367 1103 140 14 53.5

06004-41.2 2_7 1994 760 206 232.4 1321 115 700 6.44 3008 451 1333 174 18 67.7

06004-41.2 2_8 1563 612 166 202.7 1090 91 486 5.14 2512 372 1132 143 15 54.1

06004-41.2 2_9 1258 420 107 138.2 732 61 391 3.44 1852 290 795 98 10 36.3

06004-41.2 2_10 1538 533 139 183.4 936 79 429 4.52 2260 342 989 124 13 48.8

06005-44.2 1_1 3504 429 172 141.7 599 78 1110 8.56 2533 547 639 84 18 80.5

06005-44.2 1_2 2501 319 129 109 443 59 758 6.41 1878 383 480 63 14 60.5

06005-44.2 3_1 3034 336 159 86.5 418 65 1377 11 1806 424 398 62 19 93.1

06005-44.2 3_2 2862 320 138 92.7 425 60 1192 8.91 1862 426 445 62 16 76.1

06005-44.2 3_3 2491 286 131 79.9 369 55 1063 8.43 1537 347 360 55 15 72.6

06005-44.2 4_1 3233 352 149 101.2 483 65 1138 8.78 2057 458 477 67 17 75.8

06005-44.2 4_2 4350 480 197 148.8 679 87 1386 9.92 2903 627 698 95 21 91.7

06005-44.2 5_1 174 16.45 8.23 4.2 18,3 3.26 71 0.68 76.7 20.9 17.2 2.82 1.11 5.4

06005-44.2 5_2 167 17.52 8.8 4.8 20,7 3.37 61 0.58 86 21.2 21.2 3.22 1.04 5.2

06005-44.2 6_1 4699 568 227 173.8 809 106 1622 11.5 3215 698 798 111 24 105

06005-44.2 6_2 3169 370 158 109.4 489 69 1180 9.45 2057 451 496 72 18 83

07047-38.7 1_1 1789 197 84 62.2 278 37 558 4.62 1136 258 275 39 9 39.4

07047-38.7 1_2 1437 162 69 52.8 220 30 454 3.79 915 206 226 32 8 33.6

07047-38.7 2_1 4983 578 234 176.5 810 106 1592 12.2 3444 748 826 112 25 108.9

07047-38.7 2_2 5394 632 256 189.5 901 118 1697 13 3768 816 921 126 27 118

07047-38.7 3_1 5479 611 264 181.7 882 118 1766 13.6 3606 783 884 122 29 124.6

07047-38.7 3_2 5340 567 240 169.7 820 108 1764 12.9 3555 777 839 111 26 115

07047-38.7 4_1 4973 543 228 157.6 768 103 1679 13 3240 716 772 106 25 112.5

07047-38.7 4_2 5326 585 252 172 821 110 1786 13.5 3551 778 850 117 27 117.7

07047-38.7 5_1 3975 425 194 122 588 83 1360 11.4 2453 556 588 83 22 95.5

07047-38.7 5_2 3554 416 180 112.6 553 79 1237 11.1 2263 502 544 80 21 94.5

07047-38.7 5_3 8194 797 323 262.7 1140 144 2702 19.4 5005 1110 1204 158 36 168.1

13 Table 3. Continued.

Figure 5-16 depicts x-ray maps of individual thin sections, the specific spots that were analyzed during the spectrometry session of these thin sections, and spider diagrams illustrating the enrichment of rare-earth elements. The x-ray maps are used to highlight the distribution of P bearing phases and thus the location of apatites.

Sample Spot Ce

ppm Dy ppm

Er ppm

Eu ppm

Gd ppm

Ho ppm

La ppm

Lu ppm

Nd ppm

Pr ppm

Sm ppm

Tb ppm

Tm ppm

Yb ppm

07050-15.0 1_1 1018 105 45 34.8 132 19 315 2.59 564 132 142 19 5 22.9

07050-15.0 2_1 1288 139 76 38.9 149 29 530 5.86 580 151 133 23 9 46.7

07050-15.0 2_2 1421 150 83 37.6 169 32 552 5.76 638 166 146 25 10 47.2

07050-15.0 3_1 484 58 28 20.0 69 12 173 1.82 275 64 67 11 3 16.4

07050-15.0 3_2 1503 188 69 71.9 272 32 492 3.84 1150 235 292 38 7 35.3

07050-15.0 4_1 3806 431 174 139.8 588 78 1237 9.16 2447 554 588 82 19 83.1

07050-15.0 4_2 1169 142 60 47.0 189 26 363 3.55 784 169 191 27 7 31.3

07050-15.0 5_1 768 86 50 23.0 92 19 318 3.99 348 93 81 15 6 32.4

07050-15.0 6_1 4188 423 184 142.8 587 80 1349 10.6 2365 537 572 82 21 96.0

07050-15.0 6_2 3718 425 176 136.9 563 77 1262 10.2 2349 526 557 80 20 88.4

07050-15.0 7_1 1495 170 76 54.3 206 33 534 4.50 830 197 204 31 9 40.6

07053-45.0 1_1 889 90 40 27.7 115 17 290 2.65 488 117 111 16 5 22.3

07053-45.0 2_1 1984 209 112 48.3 256 45 893 7.16 998 235 219 36 13 59.7

07053-45.0 3_1 3732 398 173 113.9 515 75 1415 10.5 2248 511 533 73 20 90.6

07053-45.0 3_2 3322 348 164 90.0 429 68 1394 10.8 1832 451 424 65 19 93

07053-45.0 4_1 5339 556 255 149.1 731 108 2173 16.2 3037 708 704 102 29 139.5

07053-45.0 5_1 4068 406 192 106.9 512 80 1664 12.7 2174 516 504 74 23 108.7

07053-45.0 6_1 1738 188 83 61.2 239 36 611 4.86 1022 238 240 34 10 43.9

07053-45.0 6_2 6461 773 327 226.2 1071 146 2243 18.0 4398 941 1078 147 35 158

07053-45.0 7_1 4681 414 179 129 568 76 1815 11 2619 624 608 81 21 95.0

07053-45.0 8_1 767 85 50 21.8 89 19 343 4.05 370 93 81 14 6 31.6

07053-45.0 9_1 4642 543 237 151.9 728 102 1647 13.3 2981 657 716 103 26 116

07051-43.4 1_1 3644 400 179 115.1 546 77 1298 10.6 2262 516 543 75 20 91.8

07051-43.4 2_1 2429 241 124 71.2 273 48 1098 9.43 1201 303 268 42 16 77.6

07051-43.4 2_2 1999 170 92 42.9 187 35 885 7.89 854 228 188 30 12 62.7

07051-43.4 3_1 6754 623 257 231.2 898 116 2285 16.2 3913 906 932 123 29 140

07051-43.4 3_2 4592 392 179 113.4 532 77 1731 13.3 2453 611 540 75 22 107.7

07051-43.4 3_3 6540 615 252 216.9 896 113 2053 15 3901 894 920 125 28 130.1

07051-43.4 4_1 4685 565 232 161.7 746 104 1527 13.1 3178 688 773 106 26 112

07051-43.4 5_1 2530 278 121 84 364 52 823 7.17 1574 355 368 51 14 63.4

07051-43.4 6_1 6063 600 237 198.2 845 107 2247 14.6 4058 919 936 118 27 125.9

07051-43.4 6_2 2824 358 141 117.9 501 64 914 7.49 2069 430 537 70 15 70

14

Figures 5. X-ray map of entire thin section (left) depicting the distribution of P bearing phases and thus the location of apatites in KRODD06004-41.2m. The Individual spots that were analysed with spectrometer is shown to the right side of the figure.

Figure 6. Spider diagram showing the abundance in ppm (normalized to the chrondite

standard) on the y-axis for individual rare-earth elements (x-axis) obtained from spectrometry.

15

Figure 7. X-ray map of entire thin section (left) depicting the distribution of P bearing phases and thus the location of apatites in KRODD06005-44.2m. The Individual spots that were analysed with spectrometer is shown to the right side of the figure.

Figure 8. Spider diagram showing the abundance in ppm (normalized to the chrondite

standard) on the y-axis for individual rare-earth elements (x-axis) obtained from spectrometry.

16

Figure 9. X-ray map of entire thin section (left) depicting the distribution of P bearing phases and thus the location of apatites in KRODD07047-38.7m. The Individual spots that were analysed with spectrometer is shown to the right side of the figure.

Figure 10. Spider diagram showing the abundance in ppm (normalized to the chrondite

standard) on the y-axis for individual rare-earth elements (x-axis) obtained from spectrometry.

17

Figure 11. X-ray map of entire thin section (left) depicting the distribution of P bearing phases and thus the location of apatites in KRODD07050-15m. The Individual spots that were analysed with spectrometer is shown to the right side of the figure.

Figure 12. Spider diagram showing the abundance in ppm (normalized to the chrondite

standard) on the y-axis for individual rare-earth elements (x-axis) obtained from spectrometry.

18

Figure 13. X-ray map of entire thin section (left) depicting the distribution of P bearing phases and thus the location of apatites in KRODD07053-45m. The Individual spots that were analysed with spectrometer is shown to the right side of the figure.

Figure 14. Spider diagram showing the abundance in ppm (normalized to the chrondite

standard) on the y-axis for individual rare-earth elements (x-axis) obtained from spectrometry.

19

Figure 15. X-ray map of entire thin section (left) depicting the distribution of P bearing phases and thus the location of apatites in KRODD07051-43.4m. The Individual spots that were analysed with spectrometer is shown to the right side of the figure.

Figure 16. Spider diagram showing the abundance in ppm (normalized to the chrondite

standard) on the y-axis for individual rare-earth elements (x-axis) obtained from spectrometry.

20

Discussion

The lack of suitable apatites in samples of graphitic shale correlates with the previously mentioned association of rare-earths with phosphoritic shale (figure 3). In retrospect, it is therefore not a surprising discovery that apatite is the bearer of the rare-earths and that its mineralization occurs mainly in the phosphoritic lithology. As the phosphoritic shale too is the uranium-bearing part of the Fetsjön strata, and that apatite is known to be able to host uranium, it is to be expected that apatites at least hold some of the uranium content. That being said, as the analyses did not detect significant uranium enrichment, the idea of other minerals hosting the uranium becomes a likely scenario.

For this reason, extraction might not lead to the otherwise very common (and complicated) uranium accumulation.

The REE-enrichment is compelling and therefore represents a potentially lucrative deposit. Magnet metals such as Nd, Pr, Dy and Tb have increased immensely in value over the last years and exemplifies perhaps the most economically interesting rare- earth enrichments indicated in this study. However, the fact that the rare-earths are bound to apatite poses a problem, as will be evident from the next section.

Recovery

The research regarding REE recovery from apatites is lacking in comparison with that of the major REMs (monazite, bastnaesite, xenotime) but has recently been getting attention as they are common minerals often associated with rare-earths. Leaching of apatite has been studied by Battsengel et al. (2018), revealing that 1M sulfuric acid (H 2 SO 4 ) at conditions of 20° C was the most effective at dissolving heavy- and light rare-earth elements with a total recovery of 77% and 76% effectiveness correspondingly. It should be noted however, that there is no standard method of leaching REE-bearing minerals such as apatites. This is because the method of choice will depend on the mineralogy of the REE-containing phase but also the non-REE minerals in the ore (Kim et al. 2016). While in the late 1960s, lanthanides were extracted commercially in Finland using organic solvents during the production of phosphoric acid, there is no ongoing or at least large-scale commercial production of rare-earth elements from apatite (Habashi 2013).

Conclusion

The apatites found in the alum shales of Fetsjön carry rare-earth elements, primarily

light. The fact that apatites were only found in phosphoritic and not graphitic shale

corresponds with Eurobattery’s own investigations. As no distinct uranium content was

detected in the apatites, the extraction might not lead to unwanted uranium

accumulation. However, the lack of an established recovery technique of rare-earth

elements in apatites remains a large obstacle. Both are important factors that may

affect the feasibility of Fetsjön as a potential and economical mining project.

21

Acknowledgements

I would like to thank the people at Eurobattery Minerals for the opportunity and financial support so that this project could be realized. Special thanks to Jan-Olof Arnbom of Eurobattery Minerals and my supervisor Jaroslaw Majka for their continual support throughout the work on this thesis.

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