Erythrite
Bou Azzer, Morocco
This specimen measures 8cm x 6cm
Erythrite Co3(AsO4)2 .8H2O
Arsenates, a hydrous arsenate of cobalt and nickel
Color and Luster: Deep purple red to bluish pink; vitreous, pearly on cleavage plane; streak pale red to light pink
Hardness: 1.5-2.5
Cleavage: Perfect, one direction lengthwise
Fracture: flexible, sectile
Crystals: Monoclinic; crystals rare but occur in radiating groups or striated acicular and earthy crusts and in globular or reniform shapes with drusy surfaces
Photo by Mary Sutherland
Descriptions taken from
The Audubon Society Field Guide to North American Rocks and Minerals