Chemistry Reference
In-Depth Information
Oxychlorites
Thuringite
Chamosite
Delessite
12.0
10.0
1,0
8.0
0,9
0,8
6.0
0,7
0,6
0,5
4.0
0,4
0,3
2,4
2,0
0,2
0,1
0
0
4,0
5,0
5,6
6,2
7,0
8,0
Si
Figure 3.16
Nomenclature of the chlorites (after Hey, 1954).
Oxychlorites are constituents of sedimentary iron ores: chamosite (alu-
minous) in oolitic hematitic ore type (Clinton type, Anjou - Normandy dis-
trict in France) or limonitic ore type (“minette” type, Lorraine, France),
greenalite (non-aluminous) and chamosite in banded iron formations (BIF).
Metamorphic rocks
Chlorite is an important mineral in rocks of sedimentary origin and of
low to medium grade metamorphism. In low to medium pressure meta-
morphism, prograde reactions of appearance of the various index minerals
