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Kaeter, D., Barros, R., Menuge, J.F., Chew, D.M., Badenszki, E.
Two generations of cassiterite in albite-spodumene pegmatites from
SE Ireland: Implications for tin mineralisation in lithium pegmatites
3rd International Critical Metals Conference Edinburgh May 2, 2019
Tin: a critical metal?
Deemed critical for U.S. economy(U.S. Interior Department, 2018)
Metropolitan Museum of Arts
Latest tech gadgets(2000–1000 BC)
ITA (2018)
47% ITA (2018)
Indium tin oxide
Displays
Aircrafts
Solar panels
Potential use in
anodes of Li-ion batteries
Increasingly used in
conventional car batteries
Tin deposits
Veins and stockworks
Rare-element pegmatites
Greisens and skarns
→ Hydrothermal
→ Magmatic?
→ Metasomatic
Distance to granite ↓
Temperature ↑
Deep
Shallow
Regional geology
73
Data source: Geological Survey Ireland
Li(-Sn-Ta)
Sn-W
Aumore distal,
shallower
proximal,
deeper
Data source: Geological Survey Ireland
Pegmatite
lithologies
Spodumene
pegmatite
Data source: Geological Survey Ireland
Pegmatite
lithologies
Spodumene
pegmatite
Albitites (Ab*)
Data source: Geological Survey Ireland
Pegmatite
lithologies
Spodumene
pegmatite
Albitites (Ab*)
Quartz-muscovite
assemblages (QMA)
Data source: Geological Survey Ireland
Pegmatite
lithologies
Spodumene
pegmatite
Albitites (Ab*)
Quartz-muscovite
assemblages (QMA)
Trace-element zoning in muscovite
I
II
III
1000 µm
Ab*
Kfs
Kfs
Kfs
Ab*
Ab*
Kfs
Ab*
Kaeter et al. (2019): Geochimica Cosmochinica Acta 240: 98-138
The magmatic-hydrothermal transition
Kaeter et al. (2019): Geochimica Cosmochinica Acta 240: 98-138
The magmatic-hydrothermal transition
Kaeter et al. (2019): Geochimica Cosmochinica Acta 240: 98-138
The magmatic-hydrothermal transition
Kaeter et al. (2019): Geochimica Cosmochinica Acta 240: 98-138
CassiteriteSnO2
I
II
III
II
III
Cassiterite
250 µmBSEMs
Ab
QzMs
Ap
Qz
Chl
Ab
Laser pit
Laser pit
1
2
CGM = Columbite group mineral
Cassiterite
250 µmEDS
Cassiterite
250 µmCL
1
1
1
1
Alteration?
When?
2.3
2.3
2.3
2.2 2.2
2.2
2.12.1
2.1
Turbid zoning in 2.1
Ab
CGM
Trace-element zoning in cassiterite
I
II
III
II
III
1
2 2
2
500 µm
Zoning and deformation
I
II
III
II
III
1
2 2
2
Pre-2 fracturing and alteration
500 µm500 µm
Syn-2 fracturing?
Melt and fluid evolution
I
II
III
II
III
1
2 2
2
500 µm
1 1*1* 2 2
1*
1
2
2
1*
Magmatic (1) vs
Hydrothermal (2)
I
II
III
1 1*2 21*
1*
1
2
1
2
1
2
1
2
1000
100000
Magmatic cassiterite:
Less fractionated (low Ta/Nb, Hf/Zr)
High T, higher impurities
Hydrothermal cassiterite:
Highly fractionated (high Ta/Nb, Hf/Zr)
Low T, lower impurities
Supported by melt and fluid inclusion
studies as well as petrographic and
geochemical observations of cassiterite
in other pegmatites.
(e.g. Rao et al., 2009; Dewaele et al., 2011; Borisova et al., 2012;
Llorens González et al., 2017)
Cassiterite in the magmatic–hydrothermal transition
Stage I: Magmatic
Fractional crystallization from silicic melt
Enrichment in incompatible elements incl Sn
Stage II: Magmatic–metasomatic
Unmixing into two melts and fluid
(1) Magmatic cassiterite from silicic melt
(1*) Deformation and dissolution–reprecipitation
Stage III: Metasomatic–hydrothermal
Precipitation of albite and hydrothermal muscovite
Hydraulic fracturing
(2) Hydrothermal cassiterite
04/03/2019 Kaeter et al. Slide 26
Reading the mineralogical record of
multistage minerals is a key to decipher complex
crystallisation processes.
04/03/2019 Kaeter et al. Slide 27
Cassiterite precipitates after the magmatic
first stage of pegmatite formation from
both polymerized melt and later aqueous fluid.
04/03/2019 Kaeter et al. Slide 28
So what?
04/03/2019 Kaeter et al. Slide 29
Mining: Tin (and tantalum) is concentrated in
metasomatic units and might remain in the ground if the
pegmatite is specifically mined for spodumene.
Exploration: Cassiterite as indicator mineral;
mineral texture and inclusions can tell us if its source is
pegmatite or vein-system
This presentation has emanated from research supported in part by a research grant from Science Foundation Ireland (SFI) under
Grant Number 13/RC/2092 and is co-funded under the European Regional Development Fund and by iCRAG industry partners.
With support from:
Thank you for your attention.
Contact:
@DavidKaeter
Special thanks to the Warwickshire Geological Conservation Group (WGCG).
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Mineralogist 54:847–862.
Borisova AY, Thomas R, Salvi S, Candaudap F, Lanzanova A, Chmeleff J (2012) Tin and associated metal and metalloid geochemistry by
femtosecond LA-ICP-QMS microanalysis of pegmatite–leucogranite melt and fluid inclusions: new evidence for melt–melt–fluid
immiscibility. Mineralogical Magazine 76:91–113.
Dewaele S, Henjes-Kunst F, Melcher F, Sitnikova M, Burgess R, Gerdes A, Fernandez MA, Clercq FD, Muchez P, Lehmann B (2011) Late
Neoproterozoic overprinting of the cassiterite and columbite-tantalite bearing pegmatites of the Gatumba area, Rwanda (Central Africa).
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18/04/2019).
Kaeter D, Barros R, Menuge JF, Chew DM (2018) The magmatic–hydrothermal transition in rare-element pegmatites from southeast Ireland: LA-
ICP-MS chemical mapping of muscovite and columbite–tantalite. Geochimica et Cosmochimica Acta 240:96–130.
Kaeter, D., Barros, R., Menuge, J.F., in preparation. Metasomatic-hydrothermal high-field-strength element (Ti, Zr, Nb, Hf, Ta, U), tin and base metal
mineralization in albite–spodumene pegmatites from SE Ireland: Lithium pegmatites in late-orogenic Li-Sn(-W) systems.
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province, southeastern China. The Canadian Mineralogist 47:1195–1212.
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