English: Biotite, like the other micas, it is monoclinic with pseudo-hexagonal symmetry and possesses a perfect cleavage in one direction (c).
Illustration from 1911 Encyclopædia Britannica, article Biotite
This image comes from the 13th edition of the Encyclopædia Britannica or earlier. The copyrights for that book have expired in the United States because the book was first published in the US with the publication occurring before January 1, 1929. As such, this image is in the public domain in the United States.
Captions
Add a one-line explanation of what this file represents