Talk:Gneiss

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[edit] Issue with the second picture

Second picture looks like a migmatite, not gneiss. I think that it's better to remove it. Siim 19:30, 16 September 2005 (UTC)

[edit] Contradictory statements

Your article says that gneisses do not carry large quantities of micas, then it goes on to say that a gneiss may be classified as biotite gneiss. These two statements are contradictory because biotite is a mica. I suggest deleting the reference to micas.

The article on biotite actually says that it is found in gneisses.

[edit] Mica

When shales and mudstones are metamorphosed they turn initially to slates and then to coarse-grained foliated rocks rich in shiny mica called schists, and finally to coarse-banded rocks called gneisses. The Geology of Britain, Peter Toghill.

I think this means that if it is foliated or in 'leaves' like a mica then it's a schist, if it is banded (maybe blocky?) it's a gneiss. I would appreciate comments and clarification here. PeterGrecian 12:22, 31 October 2006 (UTC)