Pink chalcedony
Sulfur collection
Mineral deposits show off their colors
Azurite crystals
Minerals in Carlsbad Caverns
Gypsum flowers in Mammoth Cave
Mineral extraction
Mesolite deposit
Red tourmaline
Calcite and fluorite
Malachite nodules
1 of 11
Pink Chalcedony
A pink chalcedony shows off its beauty. Chalcedonies include many types of cryptocrystalline quartz gems and feature a number of different colors. Geologists can tell a chalcedony from the arrangement and structure of its crystals.
Photograph by blickwinkel/Alamy

Minerals

See pictures of minerals (azurite, gypsum, and others) from National Geographic.