Sheffield Mine - A native mine yielding star rubies, sapphires and garnets, for both the serious and the amateur rockhound. Wegner Quartz Crystal Mines - Arkansas' natural quartz crystals mine. Minerals of Australia and New Zealand - Information about the minerals and mineral locations in Australia and New Zealand. Gem and Mineral Exploration Company - The gold mines and miners of Cripple Creek, Teller County, Colorado, USA. Ron Coleman Mining, Inc. - Quartz crystal at the Arkansas' Old Coleman Mine. Oman Virtual Field Trip - Site designed for an education aid to students, but contains many excellent slides showing the geology of Oman. See dolerite dykes, harzburgite, and channel-fill structures. Alkali-Nuts: Mont Saint-Hilaire - Located East of Montréal, in Mont Saint-Hilaire and has become a major collecting site of rare mineral specimens. Offers mineral and assemblage guide, along with local dealer listings. Oregon Coast Agate - Rockhound's Guide to collecting/beachcombing Oregon Coast Agate. A rare glimpse of the cave of crystals - The BBC reports on Mexico’s Cave of Crystals, containing some of the largest natural selenite structures ever found.