Gemstones and Their Origins

Each gem deposit-whether of primary origin in the parent rocks; or secondary as alluvial placers in valley floors, river gravels, or the sand of oceanic shelves­ presents an eloquent chronicle of the Earth''s life story. It reveals to the expert the prodigious processes which formed the present crust of our planet, of which this volume discloses a small but exciting detail. The materials of the Ea...