When it was noticed that the grapes had a drusy surface (drusy means "covered with crystals"), the identity of "agate" was realized to be incorrect. Why? Because agate, as a variety of chalcedony, has a microcrystalline texture, while common quartz has a crystal size that can be ...
Many fine clear emeralds were produced, but most of the emerald-bearing rock was sold as "emerald matrix" for slabbing and cabochon cutting. The cabochons displayed emerald and tourmaline prisms in a white matrix of quartz and feldspar. This specimen is about 7 x 7 x 7 centimeters in size...
A tourmaline and diamond ring might serve as an exceptional Tiffany & Co. engagement ring due to the added sparkle this stone brings. Gemmological reports suggest the tourmaline comes from Mozambique, the world’s biggest site of these gems. The piece sold for HK$2,565,000 (or £262,...
” Although accessory minerals are only present in tiny quantities, they can provide useful insight into a rock’s geological history and are often used to determine a rock’s age. Common minerals for accessories are zircon, monazite, apatite, titanite, tourmaline, pyrite and other opaque ...
number of minerals that are usually clear, white, or other colors may be occasionally found in shades from the blue to violet end of the spectrum. Notable among these are barite, beryl, blue quartz, brucite, calcite, corundum, fluorite, jadeite, sillimanite, spinel, topaz, tourmaline, and ...