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 oxidationofgalena 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 | |
|---|---|
 | |
| General | |
| Category | Sulfate minerals |
| Formula (repeating unit) | PbCu[(OH)2|SO4] |
| IMA symbol | Lna[1] |
| 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 |
| Identification | |
| 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 | [2][3][4] |
Linarite was first identified in 1822. It is named after the Linares Plateau, Spain.[2] It occurs in association with brochantite, anglesite, caledonite, leadhillite, cerussite, malachite and hemimorphite.[4]
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