Macaulayite

General Information:
 Chemical Formula:
(Fe+++,Al)24Si4O43(OH)2
 Composition:
(Molecular Weight = 2,116.93 gm)
Aluminum 2.55 % Al
Iron 58.04 % Fe
Silicon 5.31 % Si
Hydrogen 0.10 % H 
Oxygen 34.01 % O 
 Empirical Formula:
Fe3+22Al2Si4O43(OH)2
 Environment:
Deeply weathered granite.
 IMA Status:
Approved IMA 1981
 Locality:
Bennachie car park, 7 km NW of Inverurie, Aberdeenshire, Scotland.
 Name Origin:
Named for the Macaulay Institute for Soil Research.
Physical Properties:
 Cleavage:
[001] Good
 Color:
blood red.
 Density:
4.41
 Habits:
Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite)., ,
 Luster:
Earthy (Dull)
 Streak:
light red
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