Handbook of Mineralogy · Quartz
Cite: Handbook of Mineralogy (Mineralogical Society of America). Named SiO2 species page, crystallography. https://www.handbookofmineralogy.org/pdfs/quartz.pdf
Mineral
Quartz · silicon dioxide
Quartz is silicon dioxide (SiO2). The Handbook of Mineralogy species PDF records hexagonal prismatic crystals, conchoidal fracture, and Mohs hardness 7. Webmineral lists the same formula and files amethyst, citrine, and rose quartz as varieties of this species, not as separate minerals. People collect points, compare hardness, wear cut stones, and display clusters. This page is the host card. The variety names live on Quartz varieties.
Cited public sources
Webmineral · Quartz
Cite: Webmineral. Named quartz species page (formula and varieties). Not inventory. https://webmineral.com/data/Quartz.shtml
USGS · Silica
Cite: U.S. Geological Survey, National Minerals Information Center. Silica statistics, industrial quartz. https://www.usgs.gov/centers/national-minerals-information-center/silica-statistics-and-information