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Category Sulfate minerals
(repeating unit)
Strunz classification 7.BC.65
Crystal system Monoclinic
Crystal class Prismatic (2/m)
(same H-M symbol)
Space group P21/m
Unit cell a = 9.701(2), b = 5.65
c = 4.69 [Å]; β = 102.65°; Z = 2
Color Deep azure blue
Crystal habit Crystals elongated and tabular; in crusts and aggregates
Twinning Common on {100}, also on {001}
Cleavage Perfect on {100}, imperfect on {001}
Fracture Conchoidal
Mohs scale hardness 2.5
Luster Sub-adamantine, vitreous
Streak Pale blue
Diaphaneity Transparent, translucent
Specific gravity 5.3 - 5.5
Optical properties Biaxial (-)
Refractive index nα = 1.809 nβ = 1.838 nγ = 1.859
Birefringence δ = 0.050
Pleochroism X = pale blue; Y = blue; Z = Prussian blue
2V angle Measured: 80°
References [1][2][3]

Linarite is a somewhat rare, crystalline mineral that is known among mineral collectors for its unusually intense, pure blue color. It is formed by the oxidation of galena and chalcopyrite and other copper sulfides. It is a combined copper lead sulfate hydroxide with formula PbCuSO4(OH)2. Linarite occurs as monoclinic prismatic to tabular crystals and irregular masses. It is easily confused with azurite, but does not react with dilute hydrochloric acid as azurite does. It has a Mohs hardness of 2.5 and a specific gravity of 5.3 - 5.5.

Linarite was first identified in 1822. It is named after the Linares Plateau, Spain.[1] It occurs in association with brochantite, anglesite, caledonite, leadhillite, cerussite, malachite and hemimorphite.[3]

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