Presented below are links to some other web sites which feature gem, rock, and mineral postage stamps.
Hans Marquardt
Mineralogie - Paläontologie - Geologie
und
Bergabaumotive auf Briefmarken
Mineral stamps (updated 2009)
Stéphane Gigandet
A collection of stamps figuring photos or images of minerals, cristals, gems, rocks, fossils and meteorites from around the world.