Strontianite
Strontianite is strontium carbonate, Sr(CO3): orthorhombic, aragonite group, hardness 3.5, density 3.76. Worked, it is 59.35% strontium; celestine is 47.70%.
Strontianite is strontium carbonate, Sr(CO3) on the IMA list: orthorhombic, aragonite group, hardness 3.5, density 3.76, named for Strontian, Scotland. Worked from the formula it is 59.35% strontium by mass, against 47.70% for celestine, the strontium sulphate. The sheet’s Strontian analysis carries 56.07% strontium, calcium taking 7.0% of the cation site.
In short
- The Sr ledger. On standard atomic weights SrCO3 has a formula mass of 147.63 and is 59.35% strontium, the same 59.35% the USGS Mineral Commodity Summaries 2026 uses to convert strontium carbonate to strontium content. celestine, SrSO4, is 47.70%, as the live celestine page has it; the USGS converts celestite ore at 43.88%. Per 20.00 g, strontianite carries 11.87 g of strontium, celestine 9.54 g.
- The calcium check. The Handbook of Mineralogy sheet’s analysis from Strontian, Scotland prints SrO 66.31, CaO 2.70, BaO 0.17 and CO2 30.35. Worked, that is 56.07% strontium, 94.5% of the pure figure, and on one carbonate cation site Sr 0.929, Ca 0.070, Ba 0.002: calcium takes 7.0% of the site. The CO2 balances the cations to a ratio of 1.001.
- Strontianite or celestine? The optics choose: strontianite is biaxial (−) with birefringence 0.150, celestine biaxial (+) with 0.008 to 0.013, both worked from the sheets. Cleavage helps: {110} nearly perfect against celestine’s perfect {001}. Documented failure: the balance barely moves, 14.68 g against 14.96 g in water for 20.00 g, 0.28 g apart, and hardness 3.5 sits inside celestine’s 3 to 3.5.
- The element’s name. The Royal Society of Chemistry periodic table says strontium is named after Strontian, a small town in Scotland, and that a mineral from a lead mine there was investigated by Adair Crawford in 1787 and shown by Thomas Charles Hope in 1791 to contain a new element. The September 2026 IMA-CNMNC Master List gives strontianite the year 1791, United Kingdom.
- Is strontianite fluorescent? The sheet prints fluorescent under UV, with no colour, by a ligature-aware search checked on the hemimorphite and willemite sheets. This page gives no colour or cause; the general picture is on fluorescent minerals explained.
| Material | Basis | Strontium by mass | Sr in 20.00 g | Density; 20.00 g in water | Birefringence; optic sign |
|---|---|---|---|---|---|
| Strontianite, pure | Sr(CO3) (IMA); formula mass 147.63 | 59.35%, worked | 11.87 g | 3.76; 14.68 g | 0.150; (−) |
| Strontianite, Strontian, Scotland | Sheet analysis: SrO 66.31, CaO 2.70, BaO 0.17, CO2 30.35 | 56.07%, worked | 11.21 g | - | - |
| Strontium carbonate (USGS) | USGS conversion factor for the compound | 59.35%, as printed | - | - | - |
| Celestine, pure | Sr(SO4) (IMA); formula mass 183.68 | 47.70%, worked | 9.54 g | 3.97; 14.96 g | 0.008 to 0.013; (+) |
| Celestine, Djebel Kebbouch, Tunisia | Sheet analysis: SrO 56.20, SO3 43.40, CaO 0.40 | 47.52%, worked | 9.50 g | - | - |
| Celestite ore (USGS) | USGS factor for gross weight of celestite ore | 43.88%, as printed | - | - | - |
What is strontianite? Strontium carbonate
Strontianite is strontium carbonate, written Sr(CO3) by the IMA and SrCO3 by the Handbook. The September 2026 IMA-CNMNC Master List gives it status G, grandfathered, with the year 1791 and the United Kingdom, its first reference in the Bergmannisches Journal of that year. The Handbook of Mineralogy sheet places it in the aragonite group, which the aragonite, witherite and cerussite sheets print too; the group’s weight ladder is on the witherite page and is not repeated here. The calcium carbonate polymorphs are on is aragonite a polymorph of calcite.
What the sheet records. Orthorhombic, point group 2/m 2/m 2/m. Crystals typically short to long prismatic, may be acicular, elongated along [001], pseudohexagonal, to 8 cm; also columnar, fibrous, rounded, granular, powdery and massive. Twinning on {110}, contact or less commonly penetration twins, repeated to give trillings and fourlings, and may be polysynthetic. Cleavage on {110} nearly perfect, on {021} poor, on {010} interrupted; fracture uneven to subconchoidal; brittle. Hardness 3.5; density 3.76 measured, 3.780 calculated.
Optics and colour. Biaxial (−), α = 1.517, β = 1.663, γ = 1.667, so the birefringence is 0.150, worked. Colorless, gray, pale yellow, pale green, yellowish brown or pale red, and may be longitudinally zoned; colorless in transmitted light. Lustre vitreous, resinous on breaks. The sheet adds that it may be thermoluminescent, is fluorescent under UV, and is cathodoluminescent under X-rays and electron beams; it prints no fluorescence colour.
How much strontium is in strontianite? The Sr ledger
The Sr ledger: pure strontianite is 59.35% strontium by mass, celestine 47.70%, so a gram of strontianite carries about a quarter more strontium. With Sr 87.62, C 12.011 and O 15.999, SrCO3 has a formula mass of 147.63; strontium is 59.35%, SrO 70.19% and CO2 29.81%. The sheet’s ideal column prints SrO 70.19 and CO2 29.81 exactly. The USGS Mineral Commodity Summaries 2026 converts strontium carbonate at 59.35% strontium and celestite ore at 43.88%.
The calcium check. The sheet’s analysis from Strontian, Scotland reads CO2 30.35, CaO 2.70, SrO 66.31 and BaO 0.17, total 99.53. Worked, that is 56.07% strontium, 94.5% of the pure figure. Put on one carbonate cation site, it is Sr 0.929, Ca 0.070 and Ba 0.002, and the CO2 balances the three cations to 1.001. Calcium is the main substitute in this analysis; the sheet gives no range across localities, and this page does not extend the figure.
What the USGS does and does not say. The 2026 strontium summary names celestite as the strontium mineral consumed in the United States and as the raw material from which strontium carbonate and other strontium compounds are produced. It does not mention strontianite, checked by text search of the saved summary, and this page makes no ore or use claim for it. The celestine page and is celestite a quartz carry celestine’s own figures.
Strontianite or celestine? Optics choose, weight does not
Celestine is the other strontium mineral collectors meet, and the two share localities and colour. The strontianite sheet lists baryte, calcite, celestine, harmotome and sulfur as associates. Celestine, SrSO4 on its sheet, is in the barite group and forms a series with barite; strontianite, SrCO3, is a carbonate in the aragonite group.
The tests that work. Optics: strontianite biaxial (−), birefringence 0.150 from α = 1.517 and γ = 1.667; celestine biaxial (+), α = 1.619 to 1.622, γ = 1.630 to 1.632, birefringence 0.008 to 0.013. Cleavage: strontianite nearly perfect on {110}; celestine perfect on {001}, good on {210}, poor on {010}. Habit: strontianite prismatic to acicular, pseudohexagonal; celestine typically tabular on {001}.
The tests that fail, documented. A 20.00 g piece reads 14.68 g in water as strontianite and 14.96 g as celestine, 0.28 g apart; a balance reading to 0.1 g barely separates them. Hardness, 3.5 against 3 to 3.5, overlaps. Colour overlaps too: both sheets list colorless and pale green. The weighing method is on how to measure specific gravity at home.
Strontianite and the element strontium
The element is named after the village, and the village gave its name to the mineral. The strontianite sheet’s Name field says the mineral is for Strontian, Scotland, source of the first specimens. The Royal Society of Chemistry periodic table says strontium is named after Strontian, a small town in Scotland.
The history, as that source gives it. In 1787 an unusual rock found in a lead mine at Strontian was investigated by Adair Crawford, an Edinburgh doctor, who realised it was a new mineral containing an unknown earth he named strontia. In 1791 Thomas Charles Hope made a fuller investigation and proved it was a new element. The metal was isolated in 1808 at the Royal Institution in London by Humphry Davy. We add no mine name; the sheet gives none. Why names end as they do is on why mineral names end in -ite.
Where strontianite is found
The Occurrence field: an uncommon low-temperature hydrothermal mineral formed in veins in limestone, marl and chalk; in geodes and concretions; rarely in hydrothermal metallic veins; common in carbonatites. The Distribution field says dozens of localities are known, nearly all in minor amounts.
The localities it names: Strontian, Argyll, Scotland; Clausthal and Bad Grund, Harz Mountains, Bräunsdorf near Freiberg, the Lützow mine at Könitz, Drensteinfurt near Hamm, and the Dreislar mine near Medebach, with fine crystals from Aschberg, Beckum, in Germany; large crystals from Oberdorf, Styria, with Leogang and Brixlegg also named, in Austria; Nepean Township, Ontario; the Strontium Hills north of Barstow, California; the Homestake mine, South Dakota; mines around Rosiclare and Cave-in-Rock, Illinois; the Winfield quarry, Pennsylvania; the Sierra Mojada district, Coahuila, Mexico; and the Kovdor, Sallanlatvi and Vouriyärvi carbonatites and the Khibiny and Lovozero massifs, Kola Peninsula, Russia.
On this site, the carbonate neighbours are calcite, aragonite and witherite; the rest of the reference section is at the species index. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.