Evidence for the use of rock crystal - a rare type of perfectly transparent quartz which forms in large hexagonal gems - has occasionally been found at prehistoric sites in the British Isles, but ...

Opinions expressed by Forbes Contributors are their own. David Bressan is a geologist who covers curiosities about Earth. “We were thrilled!” said Dr. David Grant, a researcher at the ...

Large crystals found in geodes and other rocks are relatively rare. Pink ChalcedonyA pink chalcedony shows off its beauty. Chalcedonies include many types of cryptocrystalline quartz gems and ...