Artinite

Artinite is a hydrated basic magnesium carbonate mineral with formula: Mg₂(CO₃)(OH)₂·3H₂O. It forms white silky monoclinic prismatic crystals that are often in radial arrays or encrustations. It has a Mohs hardness of 2.5 and a specific gravity of 2.

Artinite
Artinite from New Idria District, California
General
Category	Carbonate mineral
Formula	Mg2(CO3)(OH)2·3H2O
IMA symbol	Art[1]
Strunz classification	5.DA.10
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	C2/m
Unit cell	a = 16.56, b = 3.15 c = 6.22 [Å]; β = 99.15°; Z = 2
Identification
Color	White
Crystal habit	Acicular crystals, fibrous veinlets, botryoidal crusts, and spherical aggregates
Cleavage	On {100} perfect; on {001} good.
Mohs scale hardness	2.5
Luster	Vitreous, silky
Streak	White
Diaphaneity	Transparent
Specific gravity	2.01 – 2.03
Optical properties	Biaxial (−)
Refractive index	nα = 1.488 – 1.489 nβ = 1.533 – 1.534 nγ = 1.556 – 1.557
Birefringence	δ = 0.068
References	[2][3][4]

It occurs in low-temperature hydrothermal veins and in serpentinized ultramafic rocks. Associated minerals include brucite, hydromagnesite, pyroaurite, chrysotile, aragonite, calcite, dolomite and magnesite.^[2]

It was first reported in 1902 in Lombardy, Italy. It was named for Italian mineralogist, Ettore Artini (1866–1928).^[3]

Artinite sometimes forms balls of radiating, fibrous crystals. Specimen from New Idria district, California US. Size: 9.2 x 5.2 x 1.5 cm.