commonly found as crystals, crusts, or grains Uranophane Light yellow to Yellow to 2-3 light yellow yellow-orange orange color; radioactive B. Cannot be scratched by a fingernail but can be scratched by a copper penny Barite White Rather heavy; 3-3½ cleavage fragments may be flat and slab-like Calcite White Yellowish; dilute 3 hydrochloric acid fizzes on calcite; perfect cleavage in 3 directions gives rhomb-shaped fragments Muscovite (white White Light colored; 2-2½ mica) splits into thin, flat, transparent sheets that will bend without breaking Sulfur White or pale Will burn with a 1½-2½ yellow blue flame; commonly found as crystals, crusts, or grains Uranophane Light yellow to Yellow to 2-3 light yellow yellow-orange orange color; radioactive C. Cannot be scratched by a copper penny but can be scratched by an ordinary pocket knife Barite White Rather heavy; 3-3½ cleavage fragments may be flat and slab-like Opal White Curved, 5-6 conchoidal fracture; may appear glassy,