Linarite

     Linarite is a secondary mineral in the oxidized zones of lead-copper deposits. It is a fairly rare mineral and an extremely rare gem. The color of Linarite is a magnificent and intense blue and can be confused with Azurite.  Linarite which comes in Sulfate minerals category, its chemical compound name is copper lead sulfate hydroxide with formulae PbCu[(OH)₂|SO₄].  The Hardness (Mohs) of this stone is (Linarite) 2.5, and then its fracture is Conchoidal. 

     Crystals are usually very, very small; typically found as crusts of tiny crystals on a host rock. Crystals are rarely large enough for faceting but even then clean areas of these crystals are usually very small.The Refractive Index of this stone is 1.809 – 1.859 Biaxial ( – ) .  Gems are very difficult to cut due to the softness and perfect cleavage of the mineral. Linarite is also very collectible as a mineral specimen.   Linarite is available from many locations but fine crystals mainly come from the Red Gill and other mines, Caldbeck Fells, Cumbria, England; Tsumeb, Namibia; Mammoth-St. Anthony mine, Tiger, Pinal County, Arizona, USA.

Category:	Sulfate minerals
Formula:	PbCu[(OH)2|SO4]
	copper lead sulfate hydroxide
Crystallography:	Monoclinic – Prismatic
Crystal Habit:	Crystals are elongated along [010], typically tabular on [101] or [001], with about another 40 forms known, to 8 cm; in crusts and aggregates.
Twinning:	On [100], common; also on [001]

 

Cleavage:	[100] Perfect, [001] Distinct
Fracture:	Conchoidal
Tenacity:	Brittle
Hardness (Mohs):	2.5
Density:	5.3 – 5.5 (g/cm3)
Luminescence:	None
Radioactivity:	Not Radioactive
Other:	Observed to alter to Antlerite and to Cerussite with Malachite.

 

Color:	Bright to dark Azure Blue, Sky Blue
Transparency:	Transparent to Translucent
Luster:	Vitreous to Sub-Adamantine
Refractive Index:	1.809 – 1.859  Biaxial ( – )
Birefringence:	0.050
Dispersion:	Strong; r < v
Pleochroism:	Visible; X = pale blue; Y = blue; Z = Prussian blue