Is sphalerite a sulfide?
Is sphalerite a sulfide? Yes: ZnS, zinc sulfide, 67.10% zinc. Unlike galena and 62 of 80 sulfide sheets checked, its lustre is resinous, not metallic.
Yes. Sphalerite is zinc sulfide, ZnS on the IMA list, 67.10% zinc and 32.90% sulfur, and its Handbook sheet calls it the most important ore of zinc. It is a sulfide with a nonmetallic lustre, resinous to adamantine, unlike 62 of the 80 sulfide sheets checked here that print metallic. Hardness 3.5 to 4, density 3.9 to 4.1.
In short
- The verdict. Sphalerite is a sulfide. The September 2026 IMA-CNMNC Master List writes ZnS, status A, 1980 s.p.; the Handbook of Mineralogy sheet writes (Zn,Fe)S, prints “Mineral Group: Sphalerite group”, and opens its Distribution with “The most important ore of zinc.” Worked, ZnS is 67.10% zinc and 32.90% sulfur, with no oxygen: sulfur is −2, the sulfide state.
- The lustre ledger. A script read the Luster field of every sulfide and sulfosalt sheet cached here, 86 in all. 80 print one; 62 of those use the word metallic, as galena (“Metallic”) and pyrite (“Metallic, splendent”) do. 18 do not. Sphalerite, “Resinous to adamantine”, is one of the 18.
- Is sphalerite metallic or nonmetallic? Nonmetallic in lustre. Of the 15 sheets that print only non-metallic terms, nine are arsenic-bearing sulfides such as realgar, four are silver sulfosalts such as proustite, one is hypercinnabar, and one is sphalerite: the only zinc mineral among them. It is a metal ore, 67.10% zinc, that does not look metallic.
- Documented failure: “sulfide means metallic”. The rule fails on 18 of 80 sheets. It also fails the other way: cinnabar is “Adamantine, inclining to metallic when dark”, and wurtzite, the other ZnS, “Resinous, brilliant submetallic on crystal faces”. And six sheets, cobaltite among them, print no lustre at all, so the ledger cannot speak for them.
- Mineral or rock? A mineral: it has its own IMA row, and the sheet describes crystals to 30 cm. A rock is an aggregate of minerals; the difference is on crystal vs mineral: what is the difference. The pale streak, pale brown to pale yellow and white, is the hand test that goes with the lustre; see how to use a streak plate.
| Sheet | Formula (sheet) | Lustre, as printed | Word “metallic”? | Streak, as printed | Hardness | Density (meas.) |
|---|---|---|---|---|---|---|
| Sphalerite | (Zn,Fe)S | Resinous to adamantine | No | Pale brown to pale yellow and white | 3.5–4 | 3.9–4.1 |
| Wurtzite (the other ZnS) | (Zn,Fe)S | Resinous, brilliant submetallic on crystal faces | Submetallic only | Brown | 3.5–4 | 4.09 |
| Galena (associate) | PbS | Metallic | Yes | Lead-gray | 2.5–2.75 | 7.58 |
| Chalcopyrite (associate) | CuFeS2 | Metallic | Yes | Greenish black | 3.5–4 | 4.1–4.3 |
| Marcasite (associate) | FeS2 | Metallic | Yes | Grayish or brownish black | 6–6.5 | 4.887 |
| Pyrite (associate) | FeS2 | Metallic, splendent | Yes | Greenish black to brownish black | 6–6.5 | 5.018 |
| Cinnabar | HgS | Adamantine, inclining to metallic when dark; dull in friable material | Yes, qualified | Scarlet | 2–2.5 | 8.176 |
| Covellite | CuS | Submetallic, inclining to resinous | Submetallic only | Lead-gray, shining | 1.5–2 | 4.6–4.76 |
| Realgar | AsS | Resinous to greasy | No | Red-orange to red | 1.5–2 | 3.56 |
| Proustite | Ag3AsS3 | Adamantine | No | Vermilion | 2–2.5 | 5.57 |
| Bournonite | PbCuSbS3 | Brilliant to dull | No | Steel-gray to iron-black | 2.5–3 | 5.83 |
| All 86 sheets | — | 80 print a lustre; 6 print none | 62 yes; 18 no | — | — | — |
| The 18 without “metallic” | — | 15 non-metallic terms only; 2 submetallic; 1 brilliant to dull | No | — | — | — |
Is sphalerite a sulfide or a sulfate?
A sulfide. The IMA list writes sphalerite ZnS, and the Handbook of Mineralogy sphalerite sheet writes (Zn,Fe)S, because iron commonly stands in for zinc. Neither formula has oxygen. With zinc at +2, the sulfur must be −2, which is the sulfide state; in a sulfate the sulfur sits in an SO4 group at +6. That test is worked in full for lead on is anglesite a sulfate and is not repeated here. The British spelling sulphide, used on the sphalerite page, is the same word.
Its family on the IMA list. A scan of the formula column finds two rows written exactly ZnS: sphalerite (A, 1980 s.p., country unknown) and wurtzite (G, 1861, Bolivia). The sphalerite sheet calls it “Trimorphous with matraite and wurtzite”; matraite has no row on the September 2026 list. Worked on standard atomic weights, ZnS is 67.10% zinc and 32.90% sulfur, which is the sheet’s ideal column.
An ore of zinc. The sheet’s Distribution field opens “The most important ore of zinc.” Its oxidised products, smithsonite and hemimorphite, are the subject of is smithsonite a carbonate.
Is sphalerite metallic or nonmetallic? The lustre ledger
Method. Every Handbook sheet cached for this site was read with pdftotext -layout, and those whose header formula contains sulfur and no oxygen, selenium or tellurium were kept, leaving out native sulfur and rosickýite. That gives 86 sulfide and sulfosalt sheets: a working cache, not every sulfide that exists. A script cut each sheet’s Luster field and looked for the word metallic, not counting submetallic. Galena and pyrite serve as positive controls and both print metallic.
Result. 80 sheets print a lustre. 62 use the word metallic: 60 with no non-metallic term, plus boulangerite (“Metallic, may be silky”) and cinnabar. 18 do not. Of those, 15 print non-metallic terms only: nine arsenic-bearing sulfides (alacránite, anorpiment, dimorphite, getchellite, orpiment, pararealgar, realgar, uzonite, wakabayashilite), four silver sulfosalts (proustite, pyrargyrite, pyrostilpnite, xanthoconite), hypercinnabar and sphalerite. Two print submetallic: covellite and wurtzite. Bournonite prints “Brilliant to dull”.
What that means for sphalerite. Its sheet says “Resinous to adamantine” and “Transparent to translucent, opaque when iron-rich”. Of the 15 non-metallic-only sheets it is the only zinc mineral, and with wurtzite one of two zinc sulfides among the 18. So the honest answer to “metallic or nonmetallic” is: nonmetallic lustre, metallic element. The reflectance comparison with galena is already on the sphalerite page and is not repeated.
Where “sulfide means metallic” fails
Documented failure: 18 of 80. A rule of thumb that sulfides look metallic is right for 62 of the 80 sheets that print a lustre and wrong for 18, sphalerite among them. A collector who rejects a resinous brown crystal as “not a sulfide” on lustre alone will be wrong about sphalerite.
It also bends the other way. Cinnabar prints “Adamantine, inclining to metallic when dark”, and wurtzite, the same ZnS, “Resinous, brilliant submetallic on crystal faces”. Dark, iron-rich sphalerite is opaque on its sheet, so lustre in a dark piece is a weaker guide than in a pale one.
Six sheets cannot be read. Briartite, cobaltite, cubanite, digenite, freibergite and roxbyite print no Luster field at all, so the ledger says nothing about them. That is why the count is 62 of 80, not of 86. The class itself is decided by the formula, as on is enargite a sulfosalt for the sulfosalts; lustre only tells you what to expect in the hand.
Is sphalerite a mineral or a rock?
A mineral. It has its own row on the IMA list, ZnS, status A, 1980 s.p., where s.p. marks a special procedure. The sheet describes tetrahedral and dodecahedral crystals to 30 cm, and also fibrous, botryoidal, stalactitic, granular and massive forms. Massive sphalerite with other minerals in it is an ore or a rock; the sphalerite in it is still a mineral. The same test is applied to quartz on is quartz a mineral.
In the hand. Hardness 3.5 to 4; density 3.9 to 4.1, so a 20.00 g piece reads 14.87 to 15.12 g in water; streak pale brown to pale yellow and white. Galena, its associate, is metallic with a lead-grey streak; the magnet question for that pair is on is galena magnetic, and the UV question on is sphalerite UV reactive. The sheet names Alston Moor, Cumbria, as its English locality.
Zinc and cadmium. The sheet’s St Christoph analysis carries 0.28% cadmium. Hazard questions go to toxic minerals in a collection; this page is not health or safety advice. More guides are in the collecting guides. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.