Tyrolite

CaCu₅(AsO₄)₂CO₃(OH)₄·6H₂OIMA symbolTyl^[1]Strunz classification8.DM.10Crystal systemOrthorhombicCrystal classPrismatic (2/m)
(same H-M symbol)Space groupP2/c (no. 13) or C2/c (no. 15)IdentificationColorBlue to greenCrystal habitRadial or botryoidalMohs scale hardness1.5–2.0LusterVitreousDiaphaneityTranslucentSpecific gravity3.1–3.2Refractive indexnα = 1.694
nβ = 1.726
nγ = 1.730References^[2]

Tyrolite is a hydrous calcium copper arsenate carbonate mineral with the formula Ca Cu₅(As O₄)₂CO₃(OH)₄⋅6H₂O. Tyrolite forms glassy, blue to green orthorhombic radial crystals and botryoidal masses. It has a Mohs hardness of 1.5–2.0 and a specific gravity of 3.1–3.2. It is translucent with refractive indices of nα = 1.694, nβ = 1.726, and nγ = 1.730.

It is a secondary mineral formed by the weathering of associated copper and arsenic minerals. It was first described in 1845 for an occurrence in Schwaz, Tyrol, Austria.

Chrysocolla on tyrolite and clinotyrolite specimen (4.0 cm × 2.6 cm × 2.6 cm (1.6 in × 1.0 in × 1.0 in)); from San Simon Mine in Santa Rosa-Huantajaya District, Iquique Province, Chile.
(Click image for details of the mineral chemistry.)

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.
^ Krivovichev, S. V. (1 August 2006). "Crystal chemistry and polytypism of tyrolite". American Mineralogist. 91 (8–9): 1378–1384. Bibcode:2006AmMin..91.1378K. doi:10.2138/am.2006.2040. S2CID 96895661.