Leadhillite

Leadhillite is a lead sulfate carbonate hydroxide mineral, often associated with anglesite. It has the formula Pb4SO4(CO3)2(OH)2. Leadhillite crystallizes in the monoclinic system, but forms pseudo-hexagonal forms due to crystal twinning. It forms transparent to translucent variably colored adamantine crystals. It is quite soft with a Mohs hardness of 2.5 and a relatively high specific gravity of 6.26 to 6.55.
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(n.)
A mineral of a yellowish or greenish white color, consisting of the sulphate and carbonate of lead; -- so called from having been first found at Leadhills, Scotland.
  

General Information:
 Chemical Formula:
Pb4(SO4)(CO3)2(OH)2
 Composition:
(Molecular Weight = 1,078.90 gm)
Hydrogen 0.19 % H 
Lead 76.82 % Pb
Carbon 2.23 % C 
Sulfur 2.97 % S 
Oxygen 17.80 % O 
 Empirical Formula:
Pb4(SO4)(CO3)2(OH)2
 Name Origin:
Named after its source in Leadhills, Scotland.
Physical Properties:
 Cleavage:
[001] Perfect, [100] Indistinct
 Color:
colorless, gray, yellowish, white, or light blue.
 Density:
6.26 - 6.55, Average = 6.4
 Diaphaniety:
Transparent to translucent
 Habits:
Pseudo Hexagonal - Crystals show a hexagonal outline., Tabular - Form dimensions are thin in one direction., Massive - Granular - Common texture observed in granite and other igneous rock.
 Hardness:
2.5 - Finger Nail
 Luminescence:
None.
 Luster:
Adamantine
 Streak:
white
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