Is tourmaline a quartz
No. Quartz is SiO2; tourmaline is a boron ring silicate, 34 to 38% silica by mass. Both are hardness 7; quartz is striated across its prism, tourmaline along.
No. Tourmaline is not a quartz. Quartz is silicon dioxide, SiO2; tourmaline is a group of boron-bearing ring silicates, only 34.22% (schorl) to 38.49% (elbaite) silica by mass, worked from the IMA formulas. Both are hardness 7, so a scratch cannot separate them, but quartz prisms are striated across their length and tourmaline prisms along it.
In short
- Two different minerals, not a variety of one. The September 2026 IMA list has quartz as a single species, SiO2. Tourmaline is a group: schorl, elbaite, dravite and others. GIA describes them as sharing silicon, aluminium and boron with a complex mixture of other elements such as sodium, lithium, calcium, magnesium and iron. Tourmaline is not a colour of quartz, and quartz is not a tourmaline.
- Worked from the IMA formulas, tourmaline is about a third silica. On standard atomic weights, schorl is 34.22% SiO2 and 9.91% B2O3 by mass, elbaite 38.49% and 11.15%. The Handbook analyses are in the same range: schorl from St. Andreasberg 36.04% SiO2, elbaite from Elba 37.89% SiO2 and 10.28% B2O3. Quartz is 100% SiO2.
- The striation rule: on a crystal, quartz is striped across the prism and tourmaline along it. The Handbook's quartz sheet prints striated perpendicular to [0001], the long axis. Four of the five tourmaline sheets used here, schorl, elbaite, dravite and liddicoatite, print striated parallel to [0001]; uvite's prints no striation.
- Hardness and electricity do not decide it. Quartz is 7; schorl, elbaite and dravite are 7, so neither reliably scratches the other. Both quartz and tourmaline sheets record piezoelectric and pyroelectric behaviour. The scale does better: a 20.00 g piece reads 12.45 g in water as quartz and, on the Handbook densities, at least 13.10 g as tourmaline.
- Tourmalinated quartz is quartz. The International Gem Society describes it as clear quartz with needle-like inclusions of black tourmaline. It is two minerals in one stone, which is also why quartz heads the association lines on the schorl and elbaite sheets.
| Criterion | Quartz | Schorl (black tourmaline) | Elbaite (gem tourmaline) | Does it choose? |
|---|---|---|---|---|
| Formula (IMA list) | SiO2 | NaFe3Al6(Si6O18)(BO3)3(OH)3(OH) | Na(Al1.5Li1.5)Al6(Si6O18)(BO3)3(OH)3(OH) | Yes, by analysis |
| Silica, ideal % by mass | 100.00% | 34.22% | 38.49% | Yes, by analysis |
| Silica, Handbook analysis | SiO2 with traces | 36.04% (St. Andreasberg) | 37.89% (Elba) | - |
| Boron oxide, ideal % by mass | None | 9.91% | 11.15% | Yes, by analysis |
| Point group | 32 | 3m | 3m | - |
| Striations on the prism | Across: perpendicular to [0001] | Along: parallel to [0001] | Along: parallel to [0001] | Yes, on a crystal |
| Prism shape on the sheet | Prism {10-10} | Prominent trigonal prism and pyramid | Prominent trigonal prism and pyramid | Often, on a crystal |
| Hardness (Mohs) | 7 | 7 | 7 | No |
| Density, measured | 2.65 | 3.18 to 3.22 | 2.90 to 3.10 | Yes |
| 20.00 g piece, weight in water | 12.45 g | 13.71 to 13.79 g | 13.10 to 13.55 g | Yes: at least 0.65 g apart |
| Refractive indices | 1.544 and 1.553; uniaxial (+) | 1.635 to 1.671; uniaxial (−) | 1.615 to 1.651; uniaxial (−) | Yes |
| Electrical (sheet) | Piezoelectric and pyroelectric | Pyroelectric and piezoelectric | Pyroelectric and piezoelectric | No |
| Cleavage | Rarely observable | Very poor | Very poor | No |
Is tourmaline a quartz? The criteria that decide it
Tourmaline and quartz are separate minerals with different chemistry: quartz is pure silica, and tourmaline is a borosilicate that is only about a third silica. The Handbook of Mineralogy sheet for quartz gives SiO2, point group 32, hardness 7 and density 2.65. The schorl and elbaite sheets give point group 3m, hardness 7 and densities of 3.18 to 3.22 and 2.90 to 3.10. GIA describes the tourmalines as sharing silicon, aluminium and boron with a complex mixture of other elements.
Worked: silica and boron by mass. The IMA formulas are NaFe3Al6(Si6O18)(BO3)3(OH)3(OH) for schorl and Na(Al1.5Li1.5)Al6(Si6O18)(BO3)3(OH)3(OH) for elbaite. On standard atomic weights the formula masses are 1053.36 and 936.71. Six SiO2 units, 6 × 60.083, give 34.22% and 38.49% silica; three B atoms, written as 1.5 B2O3, give 9.91% and 11.15% boron oxide. The Handbook analyses land close: 36.04% SiO2 for St. Andreasberg schorl, and 37.89% SiO2 with 10.28% B2O3 for Elba elbaite.
Who each answer is wrong for. Quartz is the wrong label for anything heavy, striated along its length or triangular in section. Tourmaline is the wrong label for a clear or purple six-sided point striated across. The species background is on quartz and tourmaline, and the identification pages are indexed at the collecting guides.
The striation rule: along the prism or across it
The striation rule: fine grooves running along a prism point to tourmaline; grooves running across it point to quartz. The Handbook's quartz sheet prints striated ⊥ [0001], perpendicular to the long axis. The schorl, elbaite, dravite and liddicoatite sheets print striated ∥ [0001], parallel to it; liddicoatite's says deeply striated.
Method. The six sheets were converted with pdftotext -layout and searched by script for a striation statement against [0001]. Text extraction turns the parallel sign into a letter and the perpendicular sign into a question mark, so each glyph was read off the rendered PDF before it was counted. Of the five tourmaline sheets, four print parallel striations; uvite's prints none. Dravite's and uvite's add that cross-sections are typically triangular with curved, convex sides.
What the rule cannot do. It needs prism faces. A tumbled stone, a bead or a faceted gem has lost them, and then the scale and the refractometer carry the test; the order is on how to tell if tourmaline is real. Quartz itself is compared with calcite on how to tell calcite from quartz.
Why scratching cannot tell tourmaline from quartz
Quartz is hardness 7, and so are schorl, elbaite and dravite, so a scratch test between them proves nothing. Of the five tourmaline sheets used here, only uvite and liddicoatite, at 7.5, are harder than quartz, and a half-point difference is not a safe test on a specimen. The method and its limits are on how to test mineral hardness properly. Treat this as a documented negative: the classic field test fails on the classic confusion.
Electricity fails too. Tourmaline's pyroelectric property is well known, but the quartz sheet also records piezoelectric and pyroelectric, so neither sheet gives a property only one of them has. No heat test is given here.
The scale works. Weight in water is mass times one minus one over density. A 20.00 g piece reads 12.45 g as quartz, the figure used on how to tell if amethyst is real, against 13.10 to 13.55 g as elbaite and 13.71 to 13.79 g as schorl. The smallest gap, quartz to the elbaite floor, is 0.65 g. The method is on how to measure specific gravity at home.
What is tourmalinated quartz?
Tourmalinated quartz is quartz containing needles of black tourmaline: two minerals, with quartz as the host. The International Gem Society describes it as clear quartz with needle-like inclusions of black tourmaline crystals, and its tourmaline article notes that tourmaline is also found as inclusions in quartz.
The sheets explain why the two meet. Quartz is the first associate named on both the schorl and the elbaite sheets, and both sheets place tourmaline in granites and granite pegmatites, where the quartz sheet also calls quartz characteristic. A pegmatite specimen of black prisms on clear quartz is, in our judgement, the commonest way a collector meets the question.
Label it as both. Quartz with schorl inclusions, or tourmalinated quartz, is accurate; tourmaline quartz as a single species is not. Cataloguing conventions are on how to label and catalogue a mineral collection. Nothing on this site is offered for sale; the wanted list is the only commercial route.