Limonite Rusty yellowish Some specimens 5-5½ brown have shiny black surface; notice streak Magnetite Black Fragments cling 6 to a magnet Pitchblende Brownish black Brownish black, 5½ greenish black, or black; radioactive; heavy; may appear dull or greasy 6. NONMETALLIC luster, WHITE color A. Can be scratched by a fingernail Cerargyrite Shiny white or Appears waxy; 1-1½ gray knife cuts it smoothly; turns violet brown to black when exposed to light Gypsum White Soft; occurs as 2 crystals or as fibrous, granular, compact, or earthy masses Talc White Knife cuts it 1 smoothly; feels soapy or greasy; splits into thin flakes B. Cannot be scratched by a fingernail but can be scratched by a copper penny Anhydrite White Commonly occurs 3-3½ as sugary-looking masses Barite White Rather heavy; 3-3½ cleavage fragments may be flat and slab-like Calcite White Dilute 3 hydrochloric acid fizzes on calcite; perfect cleavage in 3