Spodumene | |
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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 ]
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.
Spodumene is an important source of lithium, for use in ceramics, mobile phone 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 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, reducing the price to $400 in 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]
Extraction of lithium from spodumene is challenging due to the tight binding of lithium in the crystal structure. Processing methods rely on roasting at high temperature with various reagents. At temperatures in excess of 800 °C (1,470 °F), the spodumene is converted from the alpha structure to a more open beta structure from which the lithium is more easily extracted by the reagents. Suitable extraction reagents include alkali metal sulfates, such as sodium sulfate; sodium carbonate; chlorine; or hydrofluoric acid. [17]
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. [18] [19]
This section needs additional citations for verification .(November 2022) |
Hiddenite is a pale, emerald-green gem variety first reported from Alexander County, North Carolina, U.S. [20] It was named in honor of William Earl Hidden (16 February 1853 – 12 June 1918), mining engineer, mineral collector, and mineral dealer. [21] [ 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 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. [21]
Kunzite was discovered in 1902, and was named after George Frederick Kunz, Tiffany & Co's chief jeweler at the time, and a noted mineralogist. [21] It has been found in Brazil, the U.S., Canada, CIS, Mexico, Sweden, Western Australia, Afghanistan and Pakistan. [21] [22]
Triphane is the name used for yellowish varieties of spodumene. [23]
Amblygonite is a fluorophosphate mineral, (Li,Na)AlPO4(F,OH), composed of lithium, sodium, aluminium, phosphate, fluoride and hydroxide. The mineral occurs in pegmatite deposits and is easily mistaken for albite and other feldspars. Its density, cleavage and flame test for lithium are diagnostic. Amblygonite forms a series with montebrasite, the low fluorine endmember. Geologic occurrence is in granite pegmatites, high-temperature tin veins, and greisens. Amblygonite occurs with spodumene, apatite, lepidolite, tourmaline, and other lithium-bearing minerals in pegmatite veins. It contains about 10% lithium, and has been utilized as a source of lithium. The chief commercial sources have historically been the deposits of California and France.
Beryl ( BERR-əl) is a mineral composed of beryllium aluminium silicate with the chemical formula Be3Al2Si6O18. Well-known varieties of beryl include emerald and aquamarine. Naturally occurring hexagonal crystals of beryl can be up to several meters in size, but terminated crystals are relatively rare. Pure beryl is colorless, but it is frequently tinted by impurities; possible colors are green, blue, yellow, pink, and red (the rarest). It is an ore source of beryllium.
Topaz is a silicate mineral made of aluminum and fluorine with the chemical formula Al2SiO4(F, OH)2. It is used as a gemstone in jewelry and other adornments. Common topaz in its natural state is colorless, though trace element impurities can make it pale blue or golden brown to yellow-orange. Topaz is often treated with heat or radiation to make it a deep blue, reddish-orange, pale green, pink, or purple.
Tourmaline is a crystalline silicate mineral group in which boron is compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. This gemstone comes in a wide variety of colors.
A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than 1 cm (0.4 in) and sometimes greater than 1 meter (3 ft). Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic composition to granite. However, rarer intermediate composition and mafic pegmatites are known.
The mineral or gemstone chrysoberyl is an aluminate of beryllium with the formula BeAl2O4. The name chrysoberyl is derived from the Greek words χρυσός chrysos and βήρυλλος beryllos, meaning "a gold-white spar". Despite the similarity of their names, chrysoberyl and beryl are two completely different gemstones, although they both contain beryllium. Chrysoberyl is the third-hardest frequently encountered natural gemstone and lies at 8.5 on the Mohs scale of mineral hardness, between corundum (9) and topaz (8).
Pleochroism is an optical phenomenon in which a substance has different colors when observed at different angles, especially with polarized light.
Lepidolite is a lilac-gray or rose-colored member of the mica group of minerals with chemical formula K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2. It is the most abundant lithium-bearing mineral and is a secondary source of this metal. It is the major source of the alkali metal rubidium.
Petalite, also known as castorite, is a lithium aluminum tektosilicate mineral LiAlSi4O10, crystallizing in the monoclinic system. Petalite occurs as colorless, pink, grey, yellow, yellow grey, to white tabular crystals and columnar masses. It occurs in lithium-bearing pegmatites with spodumene, lepidolite, and tourmaline. Petalite is an important ore of lithium, and is converted to spodumene and quartz by heating to ~500 °C and under 3 kbar of pressure in the presence of a dense hydrous alkali borosilicate fluid with a minor carbonate component. Petalite (and secondary spodumene formed from it) is lower in iron than primary spodumene, making it a more useful source of lithium in, e.g., the production of glass. The colorless varieties are often used as gemstones.
Hiddenite is a pale-to-emerald green variety of spodumene that is sometimes used as a gemstone.
Brazilianite, whose name derives from its country of origin, Brazil, is a typically yellow-green phosphate mineral, most commonly found in phosphate-rich pegmatites.
Phenakite or phenacite is a fairly rare nesosilicate mineral consisting of beryllium orthosilicate, Be2SiO4. Occasionally used as a gemstone, phenakite occurs as isolated crystals, which are rhombohedral with parallel-faced hemihedrism, and are either lenticular or prismatic in habit: the lenticular habit is determined by the development of faces of several obtuse rhombohedra and the absence of prism faces. There is no cleavage, and the fracture is conchoidal. The Mohs hardness is high, being 7.5–8; the specific gravity is 2.96. The crystals are sometimes perfectly colorless and transparent, but more often they are greyish or yellowish and only translucent; occasionally they are pale rose-red. In general appearance the mineral is not unlike quartz, for which indeed it has been mistaken. Its name comes from Ancient Greek: φέναξ, romanized: phénax, meaning "deceiver" due to its close visual similarity to quartz, named by Nils Gustaf Nordenskiöld in 1833.
Elbaite, a sodium, lithium, aluminium boro-silicate, with the chemical composition Na(Li1.5Al1.5)Al6Si6O18(BO3)3(OH)4, is a mineral species belonging to the six-member ring cyclosilicate tourmaline group.
Lithiophilite is a mineral containing the element lithium. It is lithium manganese(II) phosphate with chemical formula LiMnPO4. It occurs in pegmatites often associated with triphylite, the iron end member in a solid solution series. The mineral with intermediate composition is known as sicklerite and has the chemical formula Li(Mn,Fe)PO4). The name lithiophilite is derived from the Greek philos (φιλός) "friend", as lithiophilite is usually found with lithium.
George Frederick Kunz was an American mineralogist and mineral collector.
Mining in Afghanistan was controlled by the Ministry of Mines and Petroleum, prior to the August 15th takeover by the Taliban. It is headquartered in Kabul with regional offices in other parts of the country. Afghanistan has over 1,400 mineral fields, containing barite, chromite, coal, copper, gold, iron ore, lead, natural gas, petroleum, precious and semi-precious stones, salt, sulfur, lithium, talc, and zinc, among many other minerals. Gemstones include high-quality emeralds, lapis lazuli, red garnet and ruby. According to a joint study by The Pentagon and the United States Geological Survey, Afghanistan has an estimated US$1 trillion of untapped minerals.
Hiddenite, North Carolina, United States, is a centre for the mining of gemstones. Three larger mines found there are Adams Mine, NAEM and the Emerald Hollow Mine. They are collectively known as the Hiddenite Gem Mines.
Greenbushes mine is an open-pit lithium mining operation located south of the town of Greenbushes, Western Australia. It is the world's largest hard-rock lithium mine, producing approximately 1.95 million tonnes of lithium spodumene annually. The mine is 250 kilometres south of Perth and 90 kilometres southeast of the port of Bunbury.
Aquamarine is a pale-blue to light-green variety of the beryl family, with its name relating to water and sea. The color of aquamarine can be changed by heat, with a goal to enhance its physical appearance. It is the birth stone of March.
The Sandawana Mines are a mining complex in Mberengwa District, Midlands Province of Zimbabwe, primarily known for its emeralds. The mines are sixty-five kilometers south of the town of Mberengwa.