Safflorite

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Safflorite
Safflorite and Calcite3 - Bouismas Mine, Bou Azzer, Tazenakht, Ouarzazate, Souss-Massa-Draa, Morocco.jpg
Safflorite and calcite from Morocco
General
Category Mineral
Formula
(repeating unit)
(Co,Fe)As2
Strunz classification 02.EB.15a
Crystal symmetry Orthorhombic dipyramidal
H-M symbol: (2/m 2/m 2/m)
Space group: Pnnm
Unit cell a = 5.173 Å, b = 5.954 Å, c = 2.999 Å; Z=2
Identification
Color Tin white, tarnishes to gray
Crystal habit Prismatic crystals, massive to fibrous
Crystal system Orthorhombic
Twinning Forms cruciform penetration twins
Cleavage Distinct on {100}
Fracture Uneven to conchoidal
Tenacity Brittle
Mohs scale hardness 4.5-5.5
Luster Metallic
Streak Grayish black
Diaphaneity Opaque
Specific gravity 6.9-7.3
References [1][2][3]

Safflorite is a rare cobalt iron arsenide mineral with formula: (Co,Fe)As2. Pure safflorite would be just CoAs2, but iron is virtually always present. Safflorite is a member of the three-way substitution series of arsenides known as the loellingite or loellingite group. More than fifty percent iron makes the mineral loellingite whereas more than fifty percent nickel and the mineral is rammelsbergite. A parallel series of antimonide minerals exist.

Safflorite along with the other minerals crystallize in the orthorhombic system forming opaque gray to white massive to radiating forms, Clinosafflorite has a monoclinic symmetry. It has a mohs hardness of 4.5 and a specific gravity of 6.9 to 7.3. Twinning is common and star shaped twins are frequently found.

Polished sample of safflorite, loellingite and rammelsbergite on quartz from the St Andreasberg District, Harz Mountains

It was first described in 1835 from the Schneeberg District, Erzgebirge, Saxony, Germany. Safflorite occurs with other arsenide minerals as an accessory in silver mining districts. It alters to the arsenate erythrite in the secondary environment.

References[edit]