General Information:
Chemical Formula:
(Na,Ca,K)x(Mn++++,Mn+++)2O4·1.5(H2O)
Composition:
(Molecular Weight = 215.71 gm)
Potassium 1.81 % K
Sodium 3.20 % Na
Calcium 1.86 % Ca
Manganese 50.94 % Mn
Hydrogen 1.40 % H
Oxygen 40.79 % O
Empirical Formula:
Na0.3Ca0.1K0.1Mn4+Mn3+O4·1.5(H2O)
Environment:
Found as grains cementing gravel in a road cut 30 km N of Aberdeen. Major component of desert varnish. Deep sea Mn nodules.
IMA Status:
Approved IMA 1963
Locality:
Birness, Aberdeenshire, Scotland.
Name Origin:
Named after the locality.
Physical Properties:
Color:
dark brown or black.
Density:
3
Diaphaniety:
Subopaque
Habits:
Massive - Uniformly indistinguishable crystals forming large masses., Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite).,
Hardness:
1.5 - Between Talc and Gypsum
Luster:
Sub Metallic
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