Rocks, MInerals and Gemstones

a red or pink variety of garnet used as a gemstone

a rudaceous rock consisting of sharp fragments embedded in clay or sand

a kind of sedimentary rock resembling marble or limestone but rich in magnesium carbonate

a brown or yellow-green olivine found in igneous and metamorphic rocks and used as a gemstone

a common mineral that has a pale yellow color

any of various minerals consisting of hydrous silicates of aluminum or potassium etc. that crystallize in forms that allow perfect cleavage into very thin leaves; used as dielectrics because of their resistance to electricity

any of a group of hard crystalline minerals that consist of aluminum silicates of potassium or sodium or calcium or barium

a highly polished gem that is cut convexly but without facets

very hard mineral used as an abrasive

a laminated metamorphic rock similar to granite

a hard green mineral consisting of sodium aluminum silicate in monoclinic crystalline form; a source of jade; found principally in Burma