Is schorl black tourmaline?
Usually. Schorl, the sodium–iron tourmaline, hardness 7, density 3.18 to 3.22, is typically black (GIA), but six other species are black or nearly so too.
Usually. Schorl, NaFe2+3Al6(Si6O18)(BO3)3(OH)3(OH) on the IMA list, is the sodium–iron tourmaline, hardness 7, density 3.18 to 3.22, and GIA calls it typically black. But the sheets for fluor-schorl, oxy-schorl, foitite, feruvite, buergerite and povondraite are black or nearly black too, so only an analysis names a black crystal schorl.
In short
- Usually, on the sources. GIA’s tourmaline description says schorl is typically black and rich in iron, and the Handbook of Mineralogy schorl sheet lists only black, brownish black and bluish black. The International Gem Society tourmaline article adds that schorl can also occur in brown, blue or blue-green shades. So schorl is usually black; that does not make every black tourmaline crystal schorl.
- The label ladder. Henry and co-authors (American Mineralogist 96, 895–913, 2011) name a tourmaline from its analysis. Where boron, hydrogen, lithium and iron valence were not measured, the usual microprobe case, they allow a generalised name: a sodium, ferrous-iron, aluminium tourmaline becomes schorlitic tourmaline. With no analysis at all, the defensible label for a black crystal is tourmaline.
- The high-index flag. On their Handbook sheets the schorl family reads ω 1.660 to 1.671 (schorl), 1.660 (fluor-schorl) and 1.662 (oxy-schorl), with white, bluish white and pale gray streaks. Two black ferric-iron tourmalines read far higher: buergerite ω 1.735 with a yellow-brown streak, povondraite 1.800 to 1.820 with a brown streak. A black tourmaline with a brown streak or an index above 1.70 is not schorl on the sheets.
- Documented failure: the family itself. Schorl, fluor-schorl and oxy-schorl differ at the W site (OH, F or O); oxy-schorl also has one aluminium in place of a ferrous iron at Y. A 20.00 g piece reads 13.71 to 13.79 g, 13.75 g and 13.69 to 13.73 g in water; their indices overlap and all three are hardness 7. No balance, scratch or refractometer separates them.
- Old labels. Henry et al. list six obsolete names that mean schorl: cockle, ferroelbaite, ferroschorlite, pierrepontite, schirl and schorlite; aphrizite is a varietal name for dark gray schorl. Two names are traps: titanschorl is rutile, and schorlomite is a garnet. A script finds none of these old names on the September 2026 IMA list.
| Sheet | IMA name and formula | IMA status | Colour (sheet) | Streak (sheet) | ω (sheet) | Density | 20.00 g piece in water | USGS Table 1, best range |
|---|---|---|---|---|---|---|---|---|
| Schorl | Schorl, NaFe2+3Al6(Si6O18)(BO3)3(OH)3(OH) | Rn, 2007 s.p., Germany | Black, brownish black, bluish black | White | 1.660 to 1.671 | 3.18 to 3.22 | 13.71 to 13.79 g | 0.40 to 0.60 amp (7 samples, as schorlite) |
| Fluor-schorl | Fluor-schorl, NaFe2+3Al6(Si6O18)(BO3)3(OH)3F | A, 2010-067, Germany / Italy | Pale brownish to pale grayish-bluish black | Bluish white | 1.660 | 3.20 | 13.75 g | No row |
| Oxy-schorl | Oxy-schorl, Na(Fe2+2Al)Al6(Si6O18)(BO3)3(OH)3O | A, 2011-011 | Greenish to brownish black | Pale gray | 1.662 | 3.17 to 3.19 | 13.69 to 13.73 g | No row |
| Foitite | Foitite, ☐(Fe2+2Al)Al6(Si6O18)(BO3)3(OH)3(OH) | A, 1992-034, USA | Bluish black | Grayish white | 1.664 | 3.17 | 13.69 g | No row |
| Feruvite | Feruvite, CaFe2+3(Al5Mg)(Si6O18)(BO3)3(OH)3(OH) | A, 1987-057, New Zealand | Dark brown-black | Gray | 1.687 | 3.207 | 13.76 g | No row |
| Buergerite | Fluor-buergerite, NaFe3+3Al6(Si6O18)(BO3)3O3F | Rd, 1965-005, Mexico | Dark brown to almost black, bronze schiller | Yellow-brown | 1.735 | 3.31 | 13.96 g | No row |
| Povondraite | Povondraite, NaFe3+3(Fe3+4Mg2)(Si6O18)(BO3)3(OH)3O | Rn, 1990 s.p., Bolivia | Black | Brown | 1.800 to 1.820 | 3.26 | 13.87 g | No row |
| Dravite | Dravite, NaMg3Al6(Si6O18)(BO3)3(OH)3(OH) | G, 1884, Slovenia | Brown to black, red, yellow, blue, green, colourless, white | Light brown, white | 1.634 to 1.661 | 3.03 to 3.18 | 13.40 to 13.71 g | 0.60 to 0.70; brown 1.40 to 1.50 amp |
Is all black tourmaline schorl? What the sources say
Schorl is typically black on GIA’s wording, and the sources support usually, not always. GIA’s tourmaline description lists schorl among the major tourmaline species and says it is typically black and rich in iron, forms in a wide variety of rock types and is rarely used as a gem. The Handbook of Mineralogy schorl sheet gives black, brownish black and bluish black, with a white streak, hardness 7, density 3.18 to 3.22, prisms to 1.5 m and point group 3m. The International Gem Society tourmaline article says schorl can also occur in brown, blue or blue-green shades.
The other black tourmalines. The Handbook sheets fetched for this page give fluor-schorl pale brownish to pale grayish-bluish black; oxy-schorl greenish to brownish black; foitite bluish black; feruvite dark brown-black; buergerite dark brown to almost black with a bronze schiller; povondraite black; and dravite brown to black among other colours. IGS describes foitite, feruvite and povondraite in the same dark range. The group view, with its own count of the black sheets, is on tourmaline and is not repeated here.
On the IMA list. A script over the September 2026 list finds schorl as NaFe2+3Al6(Si6O18)(BO3)3(OH)3(OH), status Rn, 2007 s.p., Germany; the 2011 tourmaline nomenclature describes schorl as grandfathered, first described before the IMA existed. Both are printed because they differ. Three rows carry the name schorl: schorl, fluor-schorl and oxy-schorl. A fourth, schorlomite, Ca3Ti2(SiFe3+2)O12, is a garnet.
How is a black tourmaline named? The label ladder
Henry et al. name a tourmaline for the dominant species in the dominant subgroup, using the dominant ion of the dominant valence at each site. Their own worked example: a mixture of 40% elbaite, 35% schorl and 25% dravite is 60% alkali-subgroup 1 (schorl plus dravite) against 40% subgroup 2 (elbaite), and within subgroup 1 schorl leads, so the tourmaline is schorl, although elbaite is the largest single component.
Three rungs for a label. With a complete analysis, the name is a species: schorl (OH at W), fluor-schorl (F at W) or oxy-schorl (O at W, with Fe2+2Al at Y). The paper calls partial data without direct measurement of boron, hydrogen, lithium and the oxidation states of transition elements the most common situation, typical of tourmalines analysed only by the electron microprobe; where the estimates are judged inadequate it recommends generalised names, and a sodium, ferrous-iron, aluminium tourmaline becomes schorlitic tourmaline. With no analysis, a black prism is a tourmaline, which is how the tourmaline page reads a label.
Worked on the sheet’s analysis. The schorl sheet prints a St. Andreasberg, Germany, microprobe analysis with boron calculated from stoichiometry, lithium not determined and Fe2+:Fe3+ from Mössbauer spectroscopy. Its recalculated formula has Na 0.88 of 1.00 at X; at Y, divalent ions 1.84 of 2.84, ferrous iron 89.1% of them; and (OH)3.70 O0.30 over the four anion positions, leaving OH 0.70 against O 0.30 at W once three hydroxyls fill V. Each site reads schorl. Because boron and lithium were estimated, it is also exactly the kind of analysis for which the paper allows the generalised name.
When is a black tourmaline not schorl? The high-index flag
A black tourmaline with a brown or yellow-brown streak, or an ω above 1.70, is not schorl on the Handbook sheets. The schorl family reads ω 1.660 to 1.671 with a white (schorl), bluish white (fluor-schorl) or pale gray (oxy-schorl) streak. Foitite reads 1.664 and feruvite 1.687, with grayish white and gray streaks. Buergerite reads 1.735 with a yellow-brown streak, and povondraite 1.800 to 1.820 with a brown streak. These two are the ferric-iron species of the table; the IMA row for buergerite’s composition is now fluor-buergerite.
Where the flag stops working. Foitite and feruvite sit close to schorl: foitite’s 1.664 lies inside schorl’s range, and feruvite’s 1.687 is only 0.016 above it. Foitite has a vacant X site and feruvite calcium at X; neither difference shows in weight (13.69 and 13.76 g in water for 20.00 g against schorl’s 13.71 to 13.79 g). Separating them is an analysis. The refractometer method for tourmaline against glass, and the gap between the two readings, is on how to tell if tourmaline is real and is not repeated here; streak technique is on how to use a streak plate.
Can schorl be told from fluor-schorl or oxy-schorl? No: the documented failure
The three schorl names differ in what fills one anion site, with one aluminium for iron at Y in oxy-schorl, and no home measurement reads either. On their sheets, schorl is density 3.18 to 3.22, ω 1.660 to 1.671; fluor-schorl 3.20, ω 1.660; oxy-schorl 3.17 to 3.19, ω 1.662; all are hardness 7. Worked as 20 − 20/D, a 20.00 g piece reads 13.71 to 13.79 g, 13.75 g and 13.69 to 13.73 g in water: every fluor-schorl and oxy-schorl figure lies within 0.02 g of schorl’s range. The fluor-schorl sheet names its localities near Zschorlau, Saxony, and Grasstein, Italy; oxy-schorl’s near Zlatá Idka, Slovakia.
What this means for a label. An old schorl label on unanalysed material reads as schorl in the broad sense; it is not wrong, and it is not a species determination either. The scale still separates schorl from obsidian, as how to tell tourmaline from obsidian shows, and from quartz, as is tourmaline a quartz shows; those assets are not repeated here.
Old names on schorl labels, and is schorl magnetic?
Henry et al.’s list of obsolete and discredited tourmaline names maps six to schorl: cockle, ferroelbaite, ferroschorlite, pierrepontite, schirl and schorlite. Their list of colour varietal names gives aphrizite as dark gray schorl. Pierrepont, New York, is in the schorl sheet’s Distribution field, which reads the old pierrepontite label. Two names are traps: titanschorl (schörl) is rutile, and schorlomite was mistakenly used for schorl but is a garnet. A whole-word script finds none of the old names on the September 2026 IMA list. The paper derives schorl probably from the early German mining term Schor or from the former village Schorl, now Zschorlau, Saxony; the sheet gives an Old German word of uncertain derivation, perhaps for impurities.
Magnetic, on a laboratory separator. USGS Open-File Report 99-529, Table 1 lists schorlite, the old name for schorl, extracted at 0.20 to 0.80 amp, best range 0.40 to 0.60, from 7 samples of 125 to 150 micrometre grains. Dravite’s row reads 0.60 to 0.70, and pink to red elbaite above 1.70. the report’s text says the iron-rich end members of series such as tourmalines are more magnetic than members with less iron. That is a separator setting, not a hand-magnet test; the general picture is on which minerals are magnetic.
Where schorl is found. The sheet lists Sonnenberg near St. Andreasberg, Harz; Bovey Tracey, Devon; San Piero in Campo, Elba; the Urals; Haddam, Connecticut; Pierrepont, New York; Stony Point and Statesville, North Carolina; the Little Three mine, California; Santa Cruz, Sonora; Minas Gerais; Namibia; and Nuristan, Afghanistan. The rest is at the collecting guides. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.