raw emerald gemstone crystals inside feldspar rock with molybdenite, mica and apatite inclusions on black

blue feldspar felspar emerald mica blotches inclusion apatite molybdenite mineral stone mineralogy museum closeup black isolated rock gem geology background article catalogue crystal dark detail education encyclopedia euhedral gemstone geological mine natural ore piece poster raw science semiprecious shape surface textbook texture website material fossil shiny ural russia