Axinite is a brown to violet-brown, or reddish-brown bladed group of

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ...

s composed of

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...

aluminium Aluminium (aluminum in AmE, American and CanE, Canadian English) is a chemical element with the Symbol (chemistry), symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately o ...

boro- silicate, . Axinite is pyroelectric and

piezoelectric Piezoelectricity (, ) is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in response to applied mechanical stress. The word ' ...

. The axinite group includes: *Axinite-(Fe) or ferroaxinite, Ca₂Fe²⁺Al₂BOSi₄O₁₅(OH) iron rich, clove-brown, brown, plum-blue, pearl-gray * Axinite-(Mg) or magnesioaxinite, Ca₂MgAl₂BOSi₄O₁₅(OH) magnesium rich, pale blue to pale violet; light brown to light pink *Axinite-(Mn) or manganaxinite, Ca₂Mn²⁺Al₂BOSi₄O₁₅(OH) manganese rich, honey-yellow, clove-brown, brown to blue *Tinzenite, (CaFe²⁺Mn²⁺)₃Al₂BOSi₄O₁₅(OH) iron – manganese intermediate, yellow, brownish yellow-green Axinite is sometimes used as a gemstone.Tables of Gemstone Identification By Roger Dedeyne, Ivo Quintens p.147

Gallery

File:Axinite-64246.jpg, Clove-brown axinite crystals to 2.3 cm set atop matrix from the West Bor Pit at

Dalnegorsk Dalnegorsk (russian: Дальнего́рск, lit. ''far in the mountains'') is a town in Primorsky Krai, Russia. Population: Name It was formerly known from its founding in 1897 as Tetyukhe (russian: Те́тюхе; ; literally meaning "riv ...

, Russia File:Axinite-60191.jpg, Chloritized bladed crystals of Axinite forming on Adularia from the

Swiss Alps The Alpine region of Switzerland, conventionally referred to as the Swiss Alps (german: Schweizer Alpen, french: Alpes suisses, it, Alpi svizzere, rm, Alps svizras), represents a major natural feature of the country and is, along with the Sw ...

File:Tinzenite-Calcite-172430.jpg, Tinzenite on Calcite, 4.5 × 3.5 × 3 cm. Wessels Mine, Kalahari manganese fields, Northern Cape Province, South Africa File:Axinite-(Mn)-239862.jpg, Manganaxinite (Axinite-(Mn)), with sharp curving crystals to 4 cm. West Bor Pit at

, Russia

References

{{Manganese minerals Calcium minerals Iron(II) minerals Manganese(II) minerals Aluminium minerals Sorosilicates Triclinic minerals Luminescent minerals Gemstones Minerals in space group 2