Mineral Information and Data:

Arsenic
As [CNMNC approved formula]

Named from the Greek arrenikos or arsenikos for arsenic (later from Latin arsenicum) meaning masculin, an allusion to its potent properties, originally applied to the mineral orpiment.

IMA status : Valid species (Pre-IMA Ancient) Grandfathered
CLASSIFICATION 
Dana
(8th edition) :
01.03.01.01  
  (01) Native Elements
  (01.03) with semi-metallic and non-metallic elements
  (01.03.01) Arsenic group
  
Nickel-Strunz
(10th edition) :
01.CA.05
  (01) Elements
  (01.C) Metalloids and Nonmetals
  (01.CA) Arsenic group elements
  
Crystal system: Trigonal System
Point group (H-M): 3m (or 3 2/m) — hexagonal-scalenohedral
Unit cell: a = 3.76 Å, c = 10.55 Å
Crystal Habit: Small rhombohedral or acicular crystals; granular massive; stalactitic; reniform, reticulated
Twinning: Rare on {1014}; pressure twinning on {0112}results in delicate lamellae
  
Color: Tin-white, tarnishes dark gray
Diaphaneity: Opaque
Luster: Metallic on fresh fracture
Hardness (Mohs): 3.5
Measured Density: 5.7 to 5.73 g/cm3
Cleavage: 2; {0001} perfect, {1014} fair
Tenacity: Brittle
Fracture: Uneven
Streak: Tin-white
  
Polymorphism and Series: Dimorphous with arsenolamprite
Geologic Setting: In hydrothermal veins and deposits that contain other arsenic minerals; may be in
Co–Ag sulfide veins.
Mineral Association: Arsenolite, cinnabar, realgar, orpiment, stibnite, galena, sphalerite, pyrite, barite
  

 

Arsenic
Arsenic pseudomorph after ? on quartz
Origin: Gabe Gottes, Markirch, Alsace, France
Sample size: 10.5 x 5.5 x 4 cm
Photo: Dan Weinrich

 

Arsenic
(zoom-in of above)

 

Arsenic
Arsenic in white calcite
Origin: Criss Creek, near Savona, British Columbia, Canada
Sample size: 7 x 5 x 2.5 cm
Photo: Tom Loomis

 

Arsenic
(zoom-in of above)

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