Is quartz a mineral?
Quartz is a mineral species: SiO2, hardness 7, density 2.65. Eight IMA rows share the formula SiO2, and cultured quartz and silica glass are not minerals.
Yes. Quartz is a mineral: silicon dioxide, SiO2, hexagonal, hardness 7, density 2.65, with its own row on the September 2026 IMA list, status A, 1967 s.p. The formula alone does not make it quartz: eight IMA rows are SiO2. Cultured quartz, which is manufactured, and silica glass are not minerals.
In short
- Quartz passes every part of the definition. Tropper's EOLSS chapter defines a mineral as a naturally occurring homogeneous solid with a definite, but not fixed, chemical composition and a highly ordered atomic arrangement. Natural quartz is all four, and the IMA-CNMNC list gives it a row: SiO2, status A, 1967 s.p.
- SiO2 is not an identification. A script over the September 2026 IMA list finds 8 rows whose formula is exactly SiO2, and 2 more, mogánite and opal, written SiO2·nH2O. Same composition, different structures: on their Handbook sheets tridymite is 2.25 to 2.28, quartz 2.65 and stishovite 4.35.
- Is quartz man made? Some is, and that quartz is not a mineral specimen. The USGS says industrial cultured quartz crystal is manufactured, not mined, and that virtually all quartz crystal used in electronics is cultured. It is quartz in structure, but it fails the definition's naturally occurring test, so the honest label is synthetic or cultured quartz.
- Silica glass fails the ordered-arrangement test. The International Gem Society describes quickly chilled silica melt as silica glass with no internal structure. Same SiO2, no crystal structure, so it is not quartz and not a mineral.
- Amethyst, citrine and chalcedony are quartz. They are names within one species, not separate minerals; the variety list is on the quartz species page. Engineered quartz worktops, the other reading of is quartz man made, are a building product and outside this page.
| Name | IMA status, year | Country on the IMA list | Crystal system (Handbook) | Hardness (Handbook) | Density (Handbook) | 20.00 g piece in water |
|---|---|---|---|---|---|---|
| Quartz | A, 1967 s.p. | Unknown | Hexagonal | 7 | 2.65; 2.59 to 2.63 massive | 12.45 g |
| Tridymite | G, 1868 | Mexico | Orthorhombic, pseudohexagonal | 7 | 2.25 to 2.28 | 11.11 to 11.23 g |
| Cristobalite | G, 1887 | Mexico | Tetragonal, pseudocubic | 6 to 7 | 2.32 to 2.36 | 11.38 to 11.53 g |
| Coesite | A, 1962 s.p. | USA | Monoclinic, pseudohexagonal | 7.5 to 8 | 2.92 (calculated only) | 13.15 g |
| Stishovite | A, 1967 s.p. | USA | Tetragonal | Not determined | 4.35 (measured on synthetic) | 15.40 g |
| Seifertite | A, 2004-010 | India (meteorite) | Orthorhombic | Not determined | 4.294 (calculated only) | 15.34 g |
| Lechatelierite | Q, 1915 | Niger | No Handbook sheet | No sheet | No sheet | Not worked |
| Xiexiandeite | A, 2025-006 | Not read | No Handbook sheet | No sheet | No sheet | Not worked |
| Mogánite (SiO2·nH2O) | Rn, 1999-035 | Spain | No Handbook sheet | No sheet | No sheet | Not worked |
| Opal (SiO2·nH2O) | G, no year | Unknown | No Handbook sheet | No sheet | No sheet | Not worked |
Is quartz a mineral? The definition, clause by clause
Quartz meets each clause of the textbook definition of a mineral. Tropper, Introduction to the Mineralogical Sciences (EOLSS) defines a mineral as a naturally occurring homogeneous solid with a definite, but not fixed, chemical composition and a highly ordered atomic arrangement. The Handbook of Mineralogy quartz sheet gives quartz as SiO2, hexagonal, with prisms, over 500 forms and a distribution that opens extraordinarily common. It is a natural, crystalline solid of definite composition, and it has a row on the IMA list.
The test, as a decision rule: natural, solid, ordered, and named on the IMA list. A natural crystal of quartz passes all four. A cultured crystal fails the first; silica glass fails the third; a variety name such as amethyst passes, because the material is quartz. The difference between a mineral and a crystal of it is on crystal vs mineral.
What the definition does not say. It does not require visible crystals: the sheet uses chalcedony for quartz's fine-grained to microcrystalline habit, and massive quartz is still quartz. Nor does it depend on colour or clarity.
Is quartz just SiO2? Eight IMA rows share the formula
Eight rows on the September 2026 IMA list have the formula SiO2, exactly, and quartz is only one of them. Method: refcache text of the list (pdftotext -layout), each data row parsed into name, formula and status, and the formula matched to SiO2; an independent scan of every line for SiO2 as a separate token found the same 8. They are coesite, cristobalite, lechatelierite, quartz, seifertite, stishovite, tridymite and xiexiandeite. Two more, mogánite and opal, are written SiO2·nH2O.
Structure separates them, and their sheets say where each forms. Tridymite and cristobalite are recorded in volcanic rocks: tridymite in vesicles and as phenocrysts in felsic volcanic rocks, cristobalite as a late-crystallising phase in basaltic to rhyolitic ones. Coesite formed at pressures in excess of 20 kbar, in impact-metamorphosed rocks. Stishovite occurs at meteorite impact sites, formed by shock metamorphism of quartz, and seifertite in the Shergotty and Zagami meteorites.
The density spread shows it. Same formula, and yet on the sheets tridymite is 2.25 to 2.28, quartz 2.65 and stishovite 4.35, measured on synthetic material: 1.93 times tridymite's lowest figure. A 20.00 g quartz piece reads 12.45 g in water, the figure used across this site. The full quartz sheet is summarised on quartz.
Is quartz man made? Cultured quartz and silica glass
Cultured quartz is quartz grown in a factory, and it is not a mineral specimen. The USGS describes industrial cultured quartz crystal as electronic-grade quartz crystal that is manufactured, not mined, and says virtually all quartz crystal used in electronics is cultured. The International Gem Society says synthetic quartz comes in every colour of the rainbow and that polariscope testing no longer separates it, because some synthetics duplicate natural twinning.
Silica glass is SiO2 without the structure. The gem society describes silica melt, chilled quickly, forming silica glass with no internal structure. It fails the ordered-arrangement clause, so it is neither quartz nor a mineral. Checks for glass and grown material are on how to tell if a crystal is fake.
Out of scope. Engineered quartz worktops are a manufactured building product; this page does not cover them.
Are amethyst, citrine and chalcedony minerals?
They are quartz, so the mineral is quartz and the name is a variety. The quartz species page lists the variety names and records that none has an IMA row of its own; this page does not repeat that count. The Handbook sheet records the colours of quartz as colourless or white, and, from chemical or particulate inclusions, rose-pink to rose-red, yellow to yellowish brown, green, blue, bluish violet and brown to black.
Variety pages on this site: how to tell if amethyst is real, and for blue or black minerals mistaken for quartz, is celestite a quartz and is tourmaline a quartz. Calcite has its own comparison, how to tell calcite from quartz.
More definitions are in the collecting guides. Nothing on this site is offered for sale; the wanted list is the only commercial route.