Realgar

Realgar, α-As4S4, is an arsenic sulfide mineral. It is a soft, sectile mineral occurring in monoclinic crystals, or in granular, compact, or powdery form, often in association with the related mineral, orpiment (As2S3). It is orange-red in colour, melts at 320 °C, and burns with a bluish flame releasing fumes of arsenic and sulfur. Realgar is soft with a Mohs hardness of 1.5 to 2 and has a specific gravity of 3.5. Its molecular weight is 106.99. Its streak is orange colored. Realgar has a sub-metallic luster.
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Noun
1. a rare soft orange mineral consisting of arsenic sulphide; an important ore of arsenic
(hypernym) mineral
(substance-meronym) arsenic, As, atomic number 33

n. realgar

(n.)
Arsenic sulphide, a mineral of a brilliant red color; red orpiment. It is also an artificial product.
  

General Information:
 Chemical Formula:
AsS
 Composition:
(Molecular Weight = 106.99 gm)
Arsenic 70.03 % As
Sulfur 29.97 % S 
 Empirical Formula:
AsS
 Name Origin:
From the Arabic, rahj al ghar, "powder of the mine;"
Physical Properties:
 Cleavage:
[010] Good
 Color:
aurora red, orange yellow, or dark red.
 Density:
3.56
 Diaphaniety:
Transparent to translucent
 Habits:
Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline)., Massive - Granular - Common texture observed in granite and other igneous rock., Druse - Crystal growth in a cavity which results in numerous crystal tippe
 Hardness:
1.5-2 - Talc-Gypsum
 Luminescence:
None.
 Luster:
Sub Metallic
 Streak:
orange
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