A. Cannot be scratched by a fingernail but can be scratched by a copper penny Biotite (black mica) White Splits into thin, 2½-3 flat sheets that will bend without breaking B. Cannot be scratched by an ordinary pocket knife but can be scratched by quartz Garnet White Commonly occurs 6½-7 as crystals Quartz White Curved conchoidal 7 fracture; brownish-black smoky quartz crystals commonly 6-sided prisms with pyramid-like ends; _chalcedony_ and _chert_ may be black, too Tourmaline White Black variety is 7-7½ _schorl_; notice hardness, striations on crystals, and triangular cross section of some crystals C. Cannot be scratched by quartz Tourmaline White Black variety is 7-7½ _schorl_; notice hardness, striations on crystals, and triangular cross section of some crystals 11. NONMETALLIC luster, GREEN color