The luster is the way the surface of a mineral reflects light. The
luster of a mineral may be _nonmetallic_, _submetallic_, or _metallic_.
Mineral metals such as gold, silver, galena, and pyrite have a
_metallic_ luster. A few minerals have a luster that is almost, but not
quite metallic—their luster is _submetallic_. A mineral with a
nonmetallic luster may look _vitreous_ (glassy), _silky_, _resinous_
(like resin), _greasy_, _earthy_ (dull), _pearly_, or _adamantine_
(brilliant).