Opal: Opal is hydrated silicon dioxide. It has the same chemical composition as quartz but contains about one-tenth (and sometimes as much as one-third) water. It is never crystalline, but it displays a rich play of colors, or "fire" caused by the internal refraction of light by the array of tiny spheres of amorphous silica which for a compact, three-dimensional network in the mineral. It may be somew (read full)

Rose Quartz: Rose quartz is a usually cloudy, translucent, delicate pale pink, deep pink, rose-red to quasi-white and often veined variety of Quartz. Also known as pink quartz , rose quartz may occur more often as anhedral masses or rarely as crystals which often reach quite large sizes. Rose quartz almost always occurs in pegmatites in massive crystalline bodies which do not show crystal faces. These larg (read full)

Tektites: Tektites are glass specimens rich in silica that many believed were actually meteorites. But, the locations in which tektites have been found, and their chemistry, led scientists to suggest that they may not in fact have come from outside planet Earth. Another conjecture is that tektites are formed from rocks that melted after being hit by a meteorite. Tektites actually have a composition not unl (read full)