Baryte
Baryte is BaSO4: hardness 3 to 3.5, density 4.50, crystals to 85 cm. Of 69 white-streak sheets in our set, only it is this soft and between 4.0 and 5.0.
Baryte is barium sulphate, BaSO4: orthorhombic, hardness 3 to 3.5, measured density 4.50, perfect {001} cleavage, crystals to 85 cm. The name is Greek for weight. Of 69 white-streak sheets in this site's 176-sheet reference set, it alone is both hardness 3.5 or under and density 4.0 to 5.0.
In short
- Baryte is the IMA spelling; barite is the common US spelling, and the one the Handbook of Mineralogy uses for its sheet and its group name. The September 2026 IMA-CNMNC Master List lists baryte, Ba(SO4), with status A and the year 1971 s.p.
- The heavy-spar window. Of the 125 sheets in the set with a Streak field, 69 have a white or colourless streak. Only baryte is both hardness 3.5 or under and measured density 4.0 to 5.0. Witherite, not in the set, falls in the window too, at 4.22 to 4.31.
- Heft, worked: a 10 cm³ piece weighs 45.0 g as baryte against 27.1 g as calcite and 26.5 g as quartz, 66% and 70% more. Against celestine, 39.7 g, the margin is 13%, and that comparison is on the celestine page.
- Worked composition: BaSO4 is 58.84% barium; as oxides BaO 65.70% and SO3 34.30%, the sheet's ideal column. The Svárov analysis recalculates to Ba0.997 per sulphate.
- Crystals to 85 cm, over 70 forms. The sheet also records that baryte may change color on exposure to light, and may fluoresce and phosphoresce cream to spectral colours under UV.
| Species | Formula (Handbook) | Hardness | Density (measured) | Mass of 10 cm³ | Cleavage on the sheet | In the window? |
|---|---|---|---|---|---|---|
| Baryte | BaSO4 | 3 to 3.5 | 4.50 | 45.0 g | {001} perfect; {210} less perfect; {010} imperfect | Yes |
| Witherite (not in the set) | BaCO3 | 3 to 3.5 | 4.22 to 4.31 | 43.1 g | {010} distinct; {110}, {012} poor | Yes |
| Celestine (not in the set) | SrSO4 | 3 to 3.5 | 3.97 | 39.7 g | {001} perfect; {210} good; {010} poor | No, just below |
| Smithsonite | ZnCO3 | 4 to 4.5 | 4.43 | 44.3 g | Nearly perfect, rhombohedral | No, too hard |
| Chlorargyrite | AgCl | 2.5 | 5.556 | 55.6 g | None printed; sectile and ductile | No, too dense |
| Anglesite | PbSO4 | 2.5 to 3 | 6.38 | 63.8 g | {001} good; {210} distinct; {010} less distinct | No, too dense |
| Cerussite | PbCO3 | 3 to 3.5 | 6.55 | 65.5 g | {110} and {021} good; {010}, {012} poor | No, too dense |
| Calcite | CaCO3 | 3 | 2.7102 | 27.1 g | {10-11} perfect | No, too light |
What is baryte?
Baryte is barium sulphate, BaSO4. The IMA list gives it status A, approved, with the year 1971 s.p. The list defines s.p. as a special procedure, the year a specific action was approved by the IMA; it does not say what that action was, and neither do we. The country is given as unknown. The Handbook says it forms a series with celestine, and its group also holds anglesite and celestine on their own sheets. The name is from the Greek for weight, in allusion to the high specific gravity.
It is orthorhombic, point group 2/m 2/m 2/m, space group Pnma. The sheet says commonly in well-formed crystals, to 85 cm, with over 70 forms noted, thin to thick tabular, also prismatic or equant. It also forms crested to rosettelike aggregates of tabular individuals, and concretionary, fibrous, nodular, stalactitic, banded, granular, earthy and massive material. Hardness 3 to 3.5, measured density 4.50, calculated 4.47. Cleavage is perfect on {001}, less perfect on {210} and imperfect on {010}; fracture uneven; brittle.
It is colourless, white, yellow, brown, grey, or pale shades of red, green and blue. It may be zoned, or change color on exposure to light. That is the sheet's wording; it gives no rate or light level, and this page offers no storage advice. The streak is white, the lustre vitreous to resinous, may be pearly. Optically it is biaxial positive, α 1.636, β 1.637, γ 1.648.
Why does baryte feel so heavy? The heavy-spar window
Method. Of the 176 sheets in this site's reference set, 125 print a Streak field in their pdftotext -layout text. Of those, 69 contain white or colorless. For each, the measured density and the Mohs hardness were read by script. Neither search word contains a ligature. Sheets without a Streak field were not counted, so this rule applies to the 125.
The window: white streak, hardness 3.5 or under, measured density 4.0 to 5.0. Of the 69, only baryte is in it. The nearest sheets miss for a stated reason. Smithsonite, 4.43, is hardness 4 to 4.5. Fayalite, 4.392, is 6.5 to 7. Chlorargyrite, 5.556, is denser. Anglesite (6.38) and cerussite (6.55) are much denser. Siderite (3.96) and sphalerite (3.9 to 4.1) are harder than 3.5, and willemite and corundum far harder.
Two sheets outside the set sit on the edges. Witherite, BaCO3, is hardness 3 to 3.5 and 4.22 to 4.31, inside the window. Baryte is 4.4% to 6.6% denser, and its perfect {001} cleavage against witherite's distinct {010} is the better separator. Celestine, SrSO4, is 3.97, just under the window; the worked weighing that separates it from baryte is on the celestine page and not repeated here. How to take the reading is on how to measure specific gravity at home.
What is baryte made of? A worked composition
On standard atomic weights, BaSO4 has a formula mass of 233.383: 58.84% barium. As oxides it is BaO 65.70% and SO3 34.30%, exactly the sheet's ideal column (2).
The analysed specimen is from Svárov, Czech Republic: SO3 34.21%, BaO 65.35%, CaO 0.05%, total 99.61%. Set to one sulphate, that is Ba0.997 and Ca0.002: close to pure barium sulphate, with no strontium reported.
Heft against the common gangue minerals. Baryte's 4.50 is 1.66 times calcite's 2.7102, 1.70 times quartz's 2.65 and 1.42 times fluorite's 3.184, the upper end of fluorite's printed range. A 10 cm³ lump weighs 45.0 g as baryte and 31.8 g as fluorite. That is the practical meaning of the name. Whether barium content matters for handling is answered on is baryte toxic; this page gives no handling advice.
Where baryte is found, including Cumbria
The sheet calls baryte the most common barium mineral; many localities, even for fine crystals. It occurs as a gangue mineral in low-temperature hydrothermal veins; in residual deposits from weathered baryte-bearing limestones; as an accessory in igneous rocks and carbonatites; and in submarine volcanogenic massive sulphide deposits and sea-floor chimneys. Its associates are fluorite, calcite, dolomite, rhodochrosite, gypsum, sphalerite, galena and stibnite. Baryte is named in the Association field of 17 other sheets in the set.
The distribution, in the sheet's order: Alston Moor, Frizington, Cleator Moor and elsewhere in Cumbria; Baia Sprie and Cavnic, Romania; Příbram, Czech Republic; in Germany, the Beihilfe mine near Freiberg and the Pöhla mine in Saxony, and the Clara mine near Oberwolfach in the Black Forest; the Rock Candy mine, British Columbia; in Colorado, the Book Cliffs, Stoneham and the Bulldog Mountain mine, Creede; Elk Creek and Box Elder Creek, South Dakota; Palos Verdes, California; the Magma mine, Arizona; very fine crystals from the Miekle mine, Nevada; the El Solar mine, Taxco, Mexico; and immense crystals from the Elandsrand gold mine, Carletonville, South Africa.
The Cumbrian barium suite is on Alston Moor. The sulphates are indexed at the species index. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.