Is topaz a quartz?
No. Topaz is Al2SiO4F2, hardness 8; quartz is SiO2, hardness 7. Of nine topaz names on a gem society list of false names, six are quartz. The 1.58 line decides.
No. Topaz is an aluminium fluorosilicate, Al2SiO4F2: hardness 8, density 3.49 to 3.57, refractive indices 1.606 to 1.644. Quartz is silicon dioxide, SiO2: hardness 7, density 2.65, indices 1.544 and 1.553. The confusion is in the names: of nine topaz names on a gem society list of false names, six are quartz.
In short
- Two species, two IMA rows. The IMA-CNMNC Master List lists topaz, Al2SiO4F2, status G, and quartz, SiO2, status A, 1967 s.p. A script over the list finds no row named citrine or smoky: those are colour names for quartz. Topaz contains silicon, but worked on standard atomic weights it is only 32.65% SiO2 by mass, with aluminium and fluorine making up the rest.
- The nine-name count. The International Gem Society’s list of false or misleading gem names, from Schumann’s Gemstones of the World, has 57 entries. Nine contain the word topaz. By script: gold, Madeira, Salmanca [sic], Serra and Spanish topaz are citrine; smoky topaz is smoky quartz; King’s and Oriental topaz are yellow sapphire; Palmyra topaz is brown synthetic sapphire. Six of nine are quartz, and none is topaz.
- The 1.58 line. On a refractometer quartz reads 1.544 and 1.553, and topaz 1.606 to 1.644 on its Handbook sheet, 1.619 to 1.627 on GIA’s. Midway is 1.58: above it, not quartz; below it, not topaz. The gap is at least 0.053.
- Documented negative: birefringence. Quartz’s two indices are 0.009 apart; topaz’s highest and lowest are 0.010 apart on the sheet and 0.008 on GIA’s figures. The doubling a loupe shows is the same size in both, so it cannot choose between them.
- The weight test is on other pages. The 14.27 g floor for a 20.00 g piece is on topaz and quartz’s 12.45 g on quartz; the citrine-or-topaz carat arithmetic is on how to tell if citrine is real. None is repeated here.
| Name on the label | Actual stone (IGS list) | IMA species | Hardness (Handbook) | Refractive indices (Handbook) | Against the 1.58 line |
|---|---|---|---|---|---|
| Topaz | Topaz | Topaz, Al2SiO4F2 | 8 | 1.606 to 1.644 (GIA 1.619 to 1.627) | Above: topaz |
| Gold topaz | Citrine (quartz) | Quartz, SiO2 | 7 | 1.544 and 1.553 | Below: not topaz |
| Madeira topaz | Citrine (quartz); smoky quartz in the IGS topaz article | Quartz, SiO2 | 7 | 1.544 and 1.553 | Below: not topaz |
| Salmanca [sic] topaz | Citrine (quartz) | Quartz, SiO2 | 7 | 1.544 and 1.553 | Below: not topaz |
| Serra topaz | Citrine (quartz) | Quartz, SiO2 | 7 | 1.544 and 1.553 | Below: not topaz |
| Spanish topaz | Citrine (quartz) | Quartz, SiO2 | 7 | 1.544 and 1.553 | Below: not topaz |
| Smoky topaz | Smoky quartz | Quartz, SiO2 | 7 | 1.544 and 1.553 | Below: not topaz |
| King’s topaz | Yellow sapphire | Corundum, Al2O3 | 9 | 1.759 to 1.772 | Above: the line does not clear it |
| Oriental topaz (printed Oreintal) | Yellow sapphire | Corundum, Al2O3 | 9 | 1.759 to 1.772 | Above: the line does not clear it |
| Palmyra topaz | Brown synthetic sapphire | Corundum composition; made, not a mineral | Not used | Not used | Not tested here |
Is topaz a quartz? The criteria
Different chemistry. The Handbook of Mineralogy topaz sheet gives Al2SiO4(F,OH)2, orthorhombic, hardness 8, measured density 3.49 to 3.57, one perfect cleavage on {001}, read from the rendered sheet. The quartz sheet gives SiO2, hardness 7, density 2.65, cleavage rarely observable and a conchoidal fracture. Worked, topaz is 32.65% SiO2 by mass; it is a silicate, not a form of silica. Topaz is not a variety of quartz, and no quartz is a topaz.
Where the question comes from. The International Gem Society says that before the twentieth century all gems in the brown, orange and yellow range were called topaz, and that modern gemology was recognised as a science only in the 1930s. GIA says citrine’s tawny colour caused it to be confused with topaz before modern gemology, and that brown topaz is, the other way round, sometimes mistakenly called smoky quartz.
The criteria, in the order a collector can use them: the name, read against the false-name list; the refractometer, read against the 1.58 line; and, for rough, the cleavage. The same kind of question for other stones is answered on is tourmaline a quartz and is celestite a quartz; the guides are indexed at the collecting guides.
Nine topaz names, and how many are really quartz
Method. The gem society’s List of False or Misleading Gemstone Names, credited to Walter Schumann’s Gemstones of the World, 3rd edition, was saved and parsed by script into 57 pairs. The script kept every false name containing topaz, and separately every false name whose actual stone is topaz.
The count. Nine names contain topaz. Six are quartz: gold, Madeira, Salmanca [sic], Serra and Spanish topaz are citrine, and smoky topaz is smoky quartz. Three are corundum: King’s topaz and Oriental topaz, which the list prints as Oreintal, are yellow sapphire, and Palmyra topaz is brown synthetic sapphire. None of the nine is topaz. The reverse also happens: five false names on the same list are really topaz, among them Brazilian aquamarine, Brazilian ruby and Saxon diamond.
A documented disagreement. The list makes Madeira topaz citrine. The gem society’s own topaz article says smoky quartz is sometimes erroneously called smoky topaz, Brazilian topaz or Madeira topaz. We print both and choose neither: what the two sources agree on is that a Madeira topaz is quartz.
The 1.58 line: what a refractometer decides
The rule. Quartz’s indices on its sheet are 1.544 and 1.553, and GIA gives citrine 1.544 to 1.553. Topaz’s sheet gives α 1.606 to 1.634 and γ 1.616 to 1.644; GIA gives 1.619 to 1.627. The midpoint between quartz’s highest and topaz’s lowest is 1.5795: a reading above 1.58 is not quartz; a reading below it is not topaz. The gap the line sits in is 0.053 on the sheets and 0.066 on GIA’s figures.
Documented negative: the doubling. Quartz’s birefringence is 0.009 (1.553 minus 1.544). Topaz’s, γ minus α at either end of the sheet ranges, is 0.010, and 0.008 on GIA’s figures. A loupe shows doubled back facets in both; the size of the doubling does not choose between them.
Where the line does not help. Above 1.58 sits more than topaz: corundum’s sheet indices are 1.759 to 1.772, so the King’s and Oriental topaz of the old trade read as not quartz but are not topaz either. That separation is on corundum. The weight test is not repeated here; it is on topaz.
When each name is the wrong word
“Topaz” is wrong for any yellow, orange or brown stone that reads below 1.58, whatever the label says, and on the gem society’s list it is most often wrong for citrine. “Quartz” is wrong for brown topaz, the confusion GIA records in the other direction. “Smoky topaz” is, on both the list and the gem society’s topaz article, smoky quartz.
Precious topaz is a trade name for real topaz. GIA says yellowish brown to orange topaz is often called precious topaz to distinguish it from similarly coloured citrine and smoky quartz. The gem society says some vendors refer to yellow or brown quartz as topaz; this page gives no values and no buying advice.
For a collection label, the species goes first: quartz, variety citrine, or topaz, with the locality. The citrine side, including heat-treated amethyst, is on how to tell if citrine is real, and whether quartz itself counts as a mineral on is quartz a mineral. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.