Quartz from Tibet - pic courtesy of Wikipedia
Quartz is the second most abundant mineral in Earth’s continental crust, behind feldspar. There are many different varieties of quartz, several of which are semi-precious gemstones. Since antiquity, varieties of quartz have been the most commonly used minerals for making jewelry and carvings.
Pure quartz is colorless and transparent. The other colors of quartz are mixed with other minerals. This colored quartz are semi-precious stones for making jewelry and other decorative pieces.
Amethyst - pic courtesy of Wikipedia
There are many varieties of these, but I’ll just mention a few. Purple quartz is amethyst. The largest deposit is found in Brazil. Amethyst is formed when there is iron in the area.
Citrine - pic courtesy of Wikipedia
Citrine is a variety of quartz that ranges from pale yellow to brown due to the ferric impurities. Natural citrines are rare. Most commercial citrines are heat-treated amethyst, or smoky quartz's. Brazil is the leading producer of citrine. Citrine has been referred to as “money stone” due to the superstition that it would bring prosperity.
Rose Quartz - pic courtesy of Wikipedia
Rose quartz is pale pink to rose red in color. This is due to trace amounts of titanium, iron, or manganese.
A quartz crystal jug from the 16th century. This piece is in the National Museum in Warsaw.
Pic courtesy of Wikipedia
Quartz is very common in sedimentary rocks, such as sandstone and shale. Quartz is a defining essential of granite.
Almost all of the quartz crystals used today in the electronics industry are synthetic.