Is aventurine a quartz?
Usually: aventurine is quartzite, a quartz rock that glitters with fuchsite mica; hardness 7, SG 2.64 to 2.69. The word also names sunstone and goldstone glass.
Usually, yes. Aventurine is quartzite, a rock of tightly packed quartz grains, glittering from small included crystals, usually a green, chrome-rich mica called fuchsite (International Gem Society). It is quartz in mineral terms: hardness 7, specific gravity 2.64 to 2.69. But the word names an effect: aventurine feldspar is sunstone, and aventurine glass is goldstone.
In short
- The definition. The International Gem Society quartz article describes quartzite, a rock of tightly packed quartz grains, that sometimes contains small crystals that reflect light, and says this material is called aventurine; usually the included crystals are green, chrome-rich mica called fuchsite, and its density is usually 2.64 to 2.69. GIA’s 2025 review of phenomenal gemstones (Jin and co-authors, Gems and Gemology) says the name was first adopted in mineralogy for quartzite containing glimmering mica crystals.
- The host-word rule. Aventurine names the glitter, not the mineral; the word after it names the host. Aventurine quartz is quartz. Aventurine feldspar is feldspar: GIA writes that gem-quality aventurine feldspars are typically known as sunstones. Aventurine glass is goldstone, glass with copper or gold-coloured inclusions, on the International Gem Society glass article. A script over the September 2026 IMA-CNMNC Master List finds no line containing aventurine, goldstone, sunstone or quartzite.
- Documented failure: weight and refractive index. Worked as 20 − 20/D, a 20.00 g piece reads 12.42 to 12.57 g in water as aventurine quartz on the IGS density, 12.45 g as crystal quartz, 12.40 to 12.48 g as oligoclase and 12.54 to 12.65 g as labradorite. The Handbook of Mineralogy oligoclase sheet’s indices, 1.533 to 1.552, straddle quartz’s 1.544 and 1.553. Neither a balance nor a refractometer separates aventurine quartz from an oligoclase sunstone.
- What does separate them. Cleavage: the oligoclase sheet gives perfect on {001} and less perfect on {010}; quartz’s cleavage is rarely observable. Hardness: quartz 7, oligoclase, orthoclase and labradorite 6 to 6.5, glass 5 to 6 (IGS). And the platelets: chromium mica in aventurine quartz (Hobbs, 1982), hematite or copper in sunstone (GIA).
- Not jade. The International Gem Society list of false gemstone names gives Indian jade as a false name for aventurine quartz. Hobbs (1982) says fuchsite platelets dense enough to colour the stone prove that the material is not jade. The jade names are on is jade a mineral.
| Label | Host (source) | Glitter from (source) | Hardness | Density or SG | 20.00 g piece in water | Refractive index | Cleavage (sheet) | Is it quartz? |
|---|---|---|---|---|---|---|---|---|
| Aventurine, aventurine quartz | Quartzite, a quartz rock (IGS; GIA) | Usually fuchsite, green chrome-rich mica (IGS); chromium mica platelets (Hobbs) | 7 (Hobbs) | 2.64 to 2.69 (IGS); 2.66 ± 0.01 (Hobbs) | 12.42 to 12.57 g | 1.544 to 1.553 (Hobbs) | As quartz: rarely observable | Yes |
| Quartz crystal | SiO2, IMA row (sheet) | - | 7 | 2.65; 2.59 to 2.63 massive | 12.45 g | ω 1.544, ε 1.553 | Rarely observable | Yes |
| Aventurine feldspar: oligoclase sunstone | Sodic plagioclase, mostly oligoclase (GIA) | Hematite plates, askew to the cleavage (GIA) | 6 to 6.5 | 2.63 to 2.66 | 12.40 to 12.48 g | α 1.533 to 1.545, γ 1.542 to 1.552 | Perfect {001}, less perfect {010} | No: feldspar |
| Aventurine feldspar: orthoclase sunstone | Orthoclase (GIA) | Hematite blades (GIA) | 6 to 6.5 | 2.55 to 2.63 | 12.16 to 12.40 g | α 1.518 to 1.520, γ 1.522 to 1.525 | Perfect {001} and {010} | No: feldspar |
| Oregon sunstone | Mostly labradorite (GIA) | Copper platelets along the cleavage (GIA) | 6 to 6.5 | 2.68 to 2.72 | 12.54 to 12.65 g | α 1.555 to 1.565, γ 1.563 to 1.573 | Perfect {001}, less perfect {010} | No: feldspar |
| Goldstone, aventurine glass | Manufactured glass (IGS; GIA) | Copper or gold-coloured inclusions (IGS) | 5 to 6 (IGS) | 2.30 to 4.50 (IGS, all glass) | 11.30 to 15.56 g | 1.470 to 1.700 (IGS, all glass) | None | No: glass |
| Indian jade | A false name for aventurine quartz (IGS) | As aventurine quartz | 7 | As aventurine quartz | As above | As above | As quartz | Yes, misnamed |
Is aventurine a quartz? The definition in one sentence
Aventurine is quartzite, a rock made of quartz grains, that glitters because it contains small flat crystals, usually green fuchsite mica. The International Gem Society quartz article defines quartzite as a rock made up of tightly packed quartz grains, formed at high temperature and pressure by metamorphism, and says that when it contains small crystals that reflect light, the material is called aventurine. It lists aventurine among quartz’s variety names as translucent to opaque quartzite with aventurescence, usually green, but also gray, yellow and brown, and gives its density as usually 2.64 to 2.69. GIA’s 2025 review of phenomenal gemstones (Jin and co-authors, Gems and Gemology) calls quartzite a metamorphic rock predominantly composed of polycrystalline quartz.
So the mineral is quartz; the specimen is a rock. Quartz has a row on the September 2026 IMA list, SiO2, status A, 1967 s.p.; a case-insensitive scan finds no line containing aventurine or quartzite. The Handbook quartz sheet gives hardness 7, density 2.65 (2.59 to 2.63 when massive) and indices ω 1.544, ε 1.553, and those are the numbers aventurine quartz gives: Hobbs (1982) lists it at RI 1.544 to 1.553, specific gravity 2.66 ± 0.01, hardness 7. The species page is quartz; the general mineral test is on is quartz a mineral and is not repeated here.
The glitter is a second mineral. Fuchsite is a green, chromium-bearing mica on both the IGS and Hobbs accounts; whether the name is a species, and what the IMA mica report puts in its place, are set out on is fuchsite a mica and muscovite. The IGS adds that other micas may form aventurine, including gray varieties and brown types from Chile.
Aventurine quartz, feldspar and glass: the host-word rule
The host-word rule: aventurine names the glitter, and the word after it names the material. GIA’s 2025 review of phenomenal gemstones defines aventurescence as the glittering effect created by isolated and visually discernible flat interfaces scattered in any transparent to translucent gemstone, mostly caused by oriented inclusions. The International Gem Society glass article says the name aventurine is now also applied to natural varieties of quartz and feldspar that display aventurescence, and that goldstone may simulate them.
Aventurine feldspar. GIA writes that gem-quality aventurine feldspars are typically known as sunstones, with two kinds of reflective inclusion found in nature, metallic copper and iron oxides. Copper sunstone is reported only from feldspar phenocrysts in certain basalts, as in Oregon sunstone, and GIA’s review says most Oregon sunstones are labradorites. Hematite sunstones, mostly from granites or pegmatites, divide into orthoclase and sodic plagioclase, oligoclase or albite. The USGS gemstones list lists sunstone under the plagioclase series as gold spangles from inclusions of hematite. The feldspar side of the question is on is sunstone a feldspar; the species are oligoclase, orthoclase and labradorite, and the identification method is on how to identify feldspar.
Aventurine glass. The IGS calls goldstone, also called aventurine glass, glass with copper or gold-coloured inclusions that cause aventurescence, and says it was most likely invented in Italy in the 17th century and named avventurina, from the Italian a ventura, by chance. GIA’s review says the glass was allegedly invented by accident in eighteenth-century Italy, citing Moretti et al. (2013). The two sources differ by a century; this page prints both. Glass sold under mineral names is covered on how to tell if a crystal is fake.
Can you tell aventurine quartz from sunstone by weight? A documented failure
No: a 20.00 g piece of aventurine quartz and one of oligoclase sunstone can read the same weight in water. Worked as 20 − 20/D: aventurine quartz at the IGS density 2.64 to 2.69 reads 12.42 to 12.57 g; at Hobbs’s 2.66 ± 0.01, 12.45 to 12.51 g; crystal quartz 12.45 g. The oligoclase sheet’s 2.63 to 2.66 reads 12.40 to 12.48 g, overlapping from 12.42 to 12.48 g. Labradorite at 2.68 to 2.72 reads 12.54 to 12.65 g, touching the top of the IGS range; orthoclase at 2.55 to 2.63 reads 12.16 to 12.40 g, just under it. The method is on how to measure specific gravity at home.
The refractometer fails on oligoclase too. Its sheet gives α 1.533 to 1.545 and γ 1.542 to 1.552, which straddle quartz’s 1.544 and 1.553. Orthoclase, at 1.518 to 1.525, sits clear below quartz, and labradorite’s lowest index, 1.555, is 0.002 above quartz’s highest. Weight and refractive index both leave aventurine quartz and an oligoclase sunstone unseparated.
What does separate them. Cleavage: each of the three feldspar sheets gives a perfect cleavage on {001} and a second on {010}; the quartz sheet says its cleavage is rarely observable. Hardness: quartz 7, the feldspars 6 to 6.5, on the sheets; the technique is on how to test mineral hardness properly. And the glitter itself: GIA describes the hematite plates in oligoclase sunstone as oriented askew relative to the cleavage planes, and the copper platelets in Oregon sunstone as lying along them, while Hobbs records aventurine quartz’s platelets as chromium mica.
Is aventurine jade? Names it travels under
No. Aventurine quartz is sold under jade names, and its mica platelets rule jade out. The International Gem Society list of false gemstone names gives Indian jade as aventurine quartz, and the gem society’s quartz article lists Indian jade among quartz misnomers as green aventurine quartz. Hobbs, The Jade Enigma (Gems and Gemology, Spring 1982) says round green platelets packed densely enough to colour the stone strongly suggest aventurine quartz, that the platelets are fuchsite, a green chromium mica, and that they prove the material is not jade; it calls aventurine quartz the only jadeite simulant that shows aventurescence. The full list of jade names is on is jade a mineral and the tests on how to tell if jade is real; neither is repeated here.
Two spectroscopes agree. Hobbs writes that aventurine quartz may show lines near 6500 and 6800 Å in the red because of the chrome mica; the IGS quartz article gives broad bands at 648 and 682 nm, about the same positions in different units. Hobbs adds that dye in aventurine collects in fractures. A spectroscope is an instrument test, not a home one; dye checks are on how to tell if a crystal is dyed.
Where the answer changes. If the label says aventurine feldspar or sunstone, the stone is a feldspar; if it says goldstone or aventurine glass, it is manufactured glass; if it says aventurine alone, the platelets and a cleavage check decide. Green chalcedony is a different quartz material again, on is chrysoprase chalcedony; whether chalcedony counts as quartz is on is chalcedony quartz. The classification questions are indexed at the collecting guides. Nothing on this site is offered for sale; the wanted list is the only commercial route.