Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 77. Chapters: Feldspar, Feldspathoid, Quartz varieties, Zeolites, Kalsilite, Agate, Amethyst, Chalcedony, Flint, Opal, Chert, Jasper, Amazonite, Menilite, Analcime, Carnelian, Orthoclase, Plagioclase, Bytownite, Labradorite, Leucite, Fused quartz, Scapolite, Stilbite, Scolecite, Petrified wood, Celsian, Erionite, Paulingite, Lake Superior agate, Onyx, ZSM-5, Gmelinite, Chrome chalcedony, Nepheline, Natrolite, Sunstone, Melanophlogite, Sodalite, Cristobalite, Tiger's eye, Rubicline, Heulandite, Pollucite, Gonnardite, Microcline, Seifertite, Thomsonite, Lazurite, Oligoclase, Stellerite, Stishovite, Albite, Laumontite, Andesine, Buddingtonite, Coesite, Anorthite, Marialite, Banalsite, Mesolite, Hyalophane, Phillipsite, Chabazite, Chrysoprase, Moganite, Mordenite, Tridymite, Amicite, Shocked quartz, Hsianghualite, Sanidine, Pietersite, Herkimer diamond, Perthite, Nosean, Smoky quartz, Petalite, Heliotrope, Hauyne, Harmotome, Tugtupite, Brewsterite, Hypothetical zeolite, Afghanite, Danburite, Cape May diamonds, Prasiolite, Ametrine, Clinoptilolite, Spectrolite, Ferrierite, Moss agate, Mozarkite, Orbicular jasper, Barrerite, Levyne, Fruit quartz, SSZ-13, Anorthoclase, Phantom crystal, Erebus Crystal, Saussurite, Hyalite, Pericline, Edingtonite, Nabesite, Adularia, Gismondine, Meionite, Akik, Geyserite, Rose de france, Alkali feldspar, Fiorite, Enhydro agate. Excerpt: Quartz is the second most abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz, several of which are semi-precious gemstones. Especially in Europe and the Middle East, varieties of quartz have been since antiquity the most commonly used minerals in the maki...