Tourmaline 
This slide shows extinct trigonal cross-sections and elongate sections displaying maximum birefringence. The matrix is quartz.
UNC sample
?
Rock type
unknown
Locality
unknown
Tourmaline This slide shows extinct trigonal cross-sections and elongate sections displaying maximum birefringence. The matrix is quartz. |
UNC sample ? | |
Rock type unknown | ||
Locality unknown | ||
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