Petalite

Silicate mineral, used in ceramic glazing

(repeating unit)LiAlSi₄O₁₀IMA symbolPtl^[1]Strunz classification9.EF.05Crystal systemMonoclinicCrystal classPrismatic (2/m)
(same H-M symbol)Space groupP2/aUnit cella = 11.737 Å,
b = 5.171 Å,
c = 7.63 Å;
β = 112.54°; Z = 2IdentificationColorColorless, grey, yellow, pink, to whiteCrystal habitTabular prismatic crystals and columnar massesTwinningCommon on {001}, lamellarCleavagePerfect on {001}, poor on {201} with 38.5° angle between the twoFractureSubconchoidalTenacityBrittleMohs scale hardness6–6.5LusterVitreous, pearly on cleavagesStreakColorlessDiaphaneityTransparent to translucentSpecific gravity2.4Optical propertiesBiaxial (+)Refractive indexn_α = 1.504, n_β = 1.510, n_γ = 1.516Birefringenceδ = 0.0122V angle82–84° measuredMelting point1350 °C^[2]Fusibility5SolubilityInsolubleReferences^[3]^[4]^[5]^[6]

Petalite, also known as castorite, is a lithium aluminum tektosilicate mineral Li Al Si₄O₁₀, 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.^[7] 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.^{[citation needed]}

Discovery and occurrence

Petalite from Paprok, Nuristan Province, Afghanistan (size: 7.3 × 2.9 × 2.4 cm)

Petalite was discovered in 1800, by Brazilian naturalist and statesman Jose Bonifacio de Andrada e Silva. Type locality: Utö Island, Haninge, Stockholm, Sweden. The name is derived from the Greek word petalon, which means leaf, alluding to its perfect cleavage.^[5]^[8]^[9]

Economic deposits of petalite are found near Kalgoorlie, Western Australia; Aracuai, Minas Gerais, Brazil; Karibib, Namibia; Manitoba, Canada; and Bikita, Zimbabwe.

The first important economic application for petalite was as a raw material for the glass-ceramic cooking ware CorningWare.^{[citation needed]} It has been used as a raw material for ceramic glazes.

References

^ 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.
^ "Petalite". Digital Fire. Retrieved 23 October 2011.
^ Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (2005). "Petalite" (PDF). Handbook of Mineralogy. Mineral Data Publishing. Retrieved 14 March 2022.
^ Webmineral
^ ^a ^b Petalite, Mindat.org
^ *Hurlbut, Cornelius S. and Klein, Cornelis, 1985, Manual of Mineralogy, Wiley, 20th ed., pp. 459–460 ISBN 0-471-80580-7
^ Deer, W. A. (2004). Framework silicates: silica minerals, feldspathoids and the zeolites (2. ed.). London: Geological Soc. p. 296. ISBN 978-1-86239-144-4.
^ D'Andraba (1800). "Des caractères et des propriétés de plusieurs nouveaux minérauxde Suède et de Norwège , avec quelques observations chimiques faites sur ces substances". Journal de Physique, de Chimie, d'Histoire Naturelle, et des Arts. 51: 239.
^ Sowerby, James (1811). Exotic mineralogy: Or, Coloured figures of foreign minerals: As a supplement to British mineralogy.