Spodumene

"Kunzite" redirects here. For the Sailor Moon character, see Dark Kingdom § Kunzite.

Spodumene
Walnut Hill Pegmatite Prospect, Huntington, Hampshire County, Massachusetts, U.S. (size: 14.2 × 9.2 × 3.0 cm)
General
Category	Inosilicate
Formula (repeating unit)	lithium aluminium silicate, LiAl(SiO3)2
IMA symbol	Spd [1]
Strunz classification	9.DA.30
Dana classification	65.1.4.1
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	C2/c
Unit cell	a = 9.46  Å, b = 8.39 Å c = 5.22 Å β = 110.17°; Z = 4
Identification
Color	Highly variable: white, colorless, gray, pink, lilac, violet, yellow and green, may be bicolored; emerald green – hiddenite; lilac – kunzite; yellow – triphane
Crystal habit	prismatic, generally flattened and elongated, striated parallel to {100}, commonly massive
Twinning	Common on {100}
Cleavage	Perfect prismatic, two directions {110} ∧ {110} at 87°
Fracture	Uneven to subconchoidal
Tenacity	Brittle
Mohs scale hardness	6.5–7
Luster	Vitreous, pearly on cleavage
Streak	white
Specific gravity	3.03–3.23
Optical properties	Biaxial (+)
Refractive index	nα = 1.648–1.661 nβ = 1.655–1.670 nγ = 1.662–1.679
Birefringence	δ = 0.014–0.018
Pleochroism	Strong in kunzite: α-purple, γ-colorless; hiddenite: α-green, γ-colorless
2V angle	54° to 69°
Fusibility	3.5
Solubility	insoluble
Other characteristics	Tenebrescence, chatoyancy
References	[2] [3] [4] [5]

Spodumene is a pyroxene mineral consisting of lithium aluminium inosilicate, Li Al(Si O ₃)₂, and is a commercially important source of lithium. It occurs as colorless to yellowish, purplish, or lilac kunzite (see below), yellowish-green or emerald-green hiddenite, prismatic crystals, often of great size. Single crystals of 14.3 m (47 ft) in size are reported from the Black Hills of South Dakota, United States. ^{[6] [7]}

The naturally-occurring low-temperature form α-spodumene is in the monoclinic system, and the high-temperature β-spodumene crystallizes in the tetragonal system. α-spodumene converts to β-spodumene at temperatures above 900 °C. ^[5] Crystals are typically heavily striated parallel to the principal axis. Crystal faces are often etched and pitted with triangular markings.^{[ not verified in body ]}

Discovery and occurrence

See also: Lithium mining

Spodumene was first described in 1800 for an occurrence in the type locality in Utö, Södermanland, Sweden. It was discovered by Brazilian naturalist Jose Bonifacio de Andrada e Silva. The name is derived from the Greek spodumenos (σποδούμενος), meaning "burnt to ashes", owing to the opaque ash-grey appearance of material refined for use in industry. ^[2]

Spodumene occurs in lithium-rich granite pegmatites and aplites. Associated minerals include: quartz, albite, petalite, eucryptite, lepidolite and beryl. ^[3]

Transparent material has long been used as a gemstone with varieties kunzite and hiddenite noted for their strong pleochroism. Source localities include Democratic Republic of Congo, Afghanistan, Australia, Brazil, Madagascar (see mining), Pakistan, Québec in Canada, and North Carolina and California in the U.S.

Since 2018, the Democratic Republic of Congo (DRC) has been known to have the largest lithium spodumene hard rock deposit in the world, with mining operations occurring in the central DRC territory of Manono, Tanganyika Province. ^[8] As of 2021, the Australian company AVZ Minerals ^[9] is developing the Manono Lithium and Tin project and has a resource size of 400 million tonnes of high grade low impurities at 1.65% lithium oxide (Li ₂ O) ^[10] spodumene hard-rock based on studies and drilling of Roche Dure, one of several pegmatites in the deposit.

Economic importance

Spodumene is an important source of lithium, for use in ceramics, mobile phones and batteries (including for automotive applications), medicine, Pyroceram and as a fluxing agent. As of 2019, around half of lithium is extracted from mineral ores, which mainly consist of spodumene. Lithium is recovered from spodumene by dissolution in acid, or extraction with other reagents, after roasting to convert it to the more reactive β-spodumene. The advantage of spodumene as a lithium source compared to brine sources is the higher lithium concentration, but at a higher extraction cost. ^[11]

In 2016, the price of spodumene concentrate was forecast to be $500–600/ton for years to come. ^[12] However, price spiked above $800 in January 2018, and production increased more than consumption, resulting in the price declining to $400 by September 2020. ^{[13] [14]}

World production of lithium via spodumene was around 80,000 metric tonnes per annum in 2018, primarily from the Greenbushes pegmatite of Western Australia and from some Chinese and Chilean sources. The Talison Minerals mine in Greenbushes, Western Australia (involving Tianqi Lithium, Albemarle Corporation and Global Advanced Metals), is reported to be the world's second largest and to have the highest grade of ore at 2.4% Li₂O (2012 figures). ^[15]

In 2020, Australia expanded spodumene mining to become the leading lithium producing country in the world. ^[16]

An important economic concentrate of spodumene, known as spodumene concentrate 6 or SC6, is a high-purity lithium ore with approximately 6 percent lithium content being produced as a raw material for the subsequent production of lithium-ion batteries for electric vehicles. ^{[17] [18]}

Refining

Extraction of lithium from spodumene, often spodumene concentrate 6 (SC6), is challenging due to the tight binding of lithium in the crystal structure.

Traditional lithium refining in the 2010s involves acid leaching of lithium-containing ores, precipitation of impurities, concentration of the lithium solution, and then conversion to lithium carbonate or lithium hydroxide. These refining methods result in significant quantities of caustic waste effluent and tailings, which are usually either highly acidic or alkali. ^[11] Suitable extraction reagents include alkali metal sulfates, such as sodium sulfate; sodium carbonate; chlorine; or hydrofluoric acid. ^[19]

Another processing method relies on pyrometallurgical processing of SC6—roasting at high temperatures exceeding 800 °C (1,470 °F) to convert the spodumene from the tightly-bound alpha structure to a more open beta structure from which the lithium is more easily extracted—then cooling and reacting with various reagents in a sequence of hydrometallurgical processing steps. Some offer the use of non-caustic reagents and result in reduced waste streams, potentially allowing the use of a closed-loop refining process. ^[20] Tesla has developed and, as of 2025, is operationalizing at scale, this process of lithium refinement that does not require strong acids to extract lithium from spodumene. Their method mixes sodium chloride with the open-beta-structure spodumene concentrate and water. Agitation at high temperatures produces a slurry rich in lithium that can be filtered and purified into lithium hydroxide. The sands and limestone waste products can be repurposed as construction materials. A $375 million Tesla refinery plant located on 1,200 acres in Robstown, Texas, is under construction using this process. It began partial operation in December 2024. The site was chosen for its proximity to the Port of Corpus Christi where spodumene can easily be imported. ^[21]

A common form of more highly refined lithium from both of the above processes is lithium hydroxide, commonly used as an input in the battery industry to manufacture lithium-ion (Li-ion) battery cathode material.

Gemstone varieties

Hiddenite

Hiddenite is a pale, emerald-green gem variety first reported from Alexander County, North Carolina, U.S. ^[22] It was named in honor of William Earl Hidden (16 February 1853 – 12 June 1918), mining engineer, mineral collector, and mineral dealer. ^{[23] [ additional citation(s) needed ]}

This emerald-green variety of spodumene is colored by chromium, just as for emeralds. Some green spodumene is colored with substances other than chromium; such stones tend to have a lighter color; they are not true hiddenite.

Kunzite

Kunzite is a purple-colored gemstone, a variety of spodumene, with the color coming from minor to trace amounts of manganese. Exposure to sunlight can fade its color. ^[23]

Kunzite was discovered in 1902, and was named after George Frederick Kunz, Tiffany & Co's chief jeweler at the time, and a noted mineralogist. ^[23] It has been found in Brazil, the U.S., Canada, CIS, Mexico, Sweden, Western Australia, Afghanistan and Pakistan. ^{[23] [24]}

• 
  An almost colorless kunzite crystal (upper left), a cut pale pink kunzite (upper right) and a greenish hiddenite crystal (below) (unknown scale)
• 
  Kunzite, Nuristan Province, Afghanistan
• 
  Hiddenite from Araçuaí, Minas Gerais, Brazil

Triphane

Triphane is the name used for yellowish varieties of spodumene. ^[25]

See also

• List of minerals

Notes

1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi: 10.1180/mgm.2021.43 . S2CID   235729616.
2. Spodumene Archived 2017-12-01 at the Wayback Machine , Mindat.org
3. Anthony, John W., Bideaux, Richard A., Bladh, Kenneth W., and Nichols, Monte C. (1990). Handbook of Mineralogy Archived 2012-05-27 at the Wayback Machine . Mineral Data Publishing, Tucson, Arizona
4. Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., ISBN   0-471-80580-7
5. Deer, Howie and Zussman, Rock Forming Minerals, v. 2 Chain Silicates, Wiley, 1963 pp. 92–98
6. Schwartz, G. (1928). "The Black Hills Mineral Region". American Mineralogist. 13: 56–63.
7. Robert Louis Bonewitz, 2005, Rock and Gem, London, Dorling Kindersley
8. "This Congo project could supply the world with lithium". MiningDotCom . 10 December 2018. Archived from the original on 14 April 2021. Retrieved 26 March 2021.
9. "AVZ Minerals Limited". AVZ Minerals . Archived from the original on 14 April 2021. Retrieved 25 March 2021.
10. "AVZ Minerals Definitive Feasibility Study (DFS – April 2020)". AVZ Minerals . Archived from the original on 2021-04-14. Retrieved 2021-03-31.
11. Rioyo, Javier; Tuset, Sergio; Grau, Ramón (12 August 2020). "Lithium Extraction from Spodumene by the Traditional Sulfuric Acid Process: A Review". Mineral Processing and Extractive Metallurgy Review. 43: 97–106. doi:10.1080/08827508.2020.1798234. ISSN   0882-7508. S2CID   225417879.
12. "Spodumene concentrate forecasted price 2020". Statista . 21 July 2016. Archived from the original on 1 December 2020.
13. Shi, Carrie; Ouerghi, Dalila (5 October 2020). "Demand pick-up halts spodumene price fall". www.metalbulletin.com. Archived from the original on 11 October 2020.
14. "Lithium Resources and Energy Quarterly" (PDF). December 2019. Archived (PDF) from the original on 22 September 2020.
15. "Greenbushes Lithium Mine". Golden Dragon Capital. Archived from the original on 19 January 2019. Retrieved 18 January 2019.
16. Jaskula, Brian W. (January 2020). "Mineral Commodity Summaries 2020" (PDF). U.S. Geological Survey. Archived (PDF) from the original on 1 November 2020. Retrieved 29 June 2020.
17. Jamasmie, Cecilia (28 September 2020). "Piedmont Lithium stock soars on confirmed Tesla deal". mining.com. Archived from the original on 16 March 2021. Retrieved 13 March 2021.
18. Piedmont Lithium Signs Sales Agreement with Tesla Archived 2021-01-26 at the Wayback Machine , 28 September 2020, retrieved 14 March 2021.
19. Choubey, Pankaj K.; Kim, Min-seuk; Srivastava, Rajiv R.; Lee, Jae-chun; Lee, Jin-Young (April 2016). "Advance review on the exploitation of the prominent energy-storage element: Lithium. Part I: From mineral and brine resources". Minerals Engineering. 89: 119–137. Bibcode:2016MiEng..89..119C. doi:10.1016/j.mineng.2016.01.010.
20. Clemens, Kevin (3 November 2023). "Tesla's lithium refinery plant on the Texas Gulf Coast is ahead of schedule and should begin production by mid-2024". EE Power. Retrieved 18 November 2024.
21. Lingle, Brandon (2024-12-16). "Tesla begins operation at its South Texas lithium refinery, firing up its kiln for first time". San Antonio Express-News. Archived from the original on 2024-12-22. Retrieved 2025-01-30.
22. Smith, John Lawrence. "Hiddenite, an emerald-green variety of spodumene. Archived 2021-08-23 at the Wayback Machine " American Journal of Science 3.122 (1881): 128–130.
23. Cook, Robert B. (1 September 1997). "Connoisseur's Choice: Spodumene var. Kunzite, Nuristan, Afghanistan". Rocks & Minerals. 72 (5): 340–343. Bibcode:1997RoMin..72..340C. doi:10.1080/00357529709605063. ISSN   0035-7529.
24. "Kunzite Gemstone | Kunzite Stone – GIA". www.gia.edu. Archived from the original on 2023-03-01. Retrieved 2023-03-01.
25. Brooks, Kent (2020). "Lithium minerals". Geology Today. 36 (5): 192–197. Bibcode:2020GeolT..36..192B. doi:10.1111/gto.12326. ISSN   1365-2451. S2CID   243253247. Archived from the original on 2021-08-23. Retrieved 2021-08-23.

References

• Kunz, George Frederick (1892). Gems and Precious Stones of North America. New York: The Scientific Publishing Company.
• Palache, C., Davidson, S. C., and Goranson, E. A. (1930). "The Hiddenite deposit in Alexander County, N. Carolina". American Mineralogist Vol. 15 No. 8 p. 280
• Webster, R. (2000). Gems: Their Sources, Descriptions and Identification (5th ed.), pp. 186–190. Great Britain: Butterworth-Heinemann.
• The key players in Quebec lithium Archived 2013-01-30 at archive.today , "Daily News", The Northern Miner, 11 August 2010.

External links

• Texts on Wikisource:
  • "Kunzite". Encyclopædia Britannica (11th ed.). 1911.
  • Rudler, Frederick William (1911). "Spodumene". Encyclopædia Britannica (11th ed.).
  • "Spodumene". New International Encyclopedia . 1905.