Colemanite (commercial)
A standard material in Glazecalc's library: its oxide analysis, unity contribution and hazards.
What it is
- Kind
- Boron sources
- Formula
- B₂O₃ 40.0%, CaO 26.8%, SiO₂ 5.0%, MgO 2.7%, SrO 1.15%, Al₂O₃ 0.25%, Na₂O 0.15%, Fe₂O₃ 0.04%, LOI 24.0%
- Made by
- Eti Maden (Turkey), sold by Etimine USA and Etimine S.A.
- Sold in
- US, EU, UK
- Source
- Etimine USA, Colemanite typical analysis (2026-02)
Turkish colemanite, Etimine’s typical analysis (standard and fine mesh). Scarce in US retail; Gerstley Borate and Gillespie Borate are the usual stand-ins.
Oxide analysis and unity formula
Glazecalc has the analysis of Colemanite (commercial) as weight percent of the raw material. The unity contribution is the moles of each oxide in the amount of Colemanite (commercial) that holds 1.0 mole of flux, which is how Glazecalc adds it into a recipe's unity formula.
| Oxide | Weight % | Unity contribution |
|---|---|---|
| B₂O₃ | 40.0 | 1.029 |
| CaO | 26.8 | 0.856 |
| SiO₂ | 5.0 | 0.149 |
| MgO | 2.7 | 0.120 |
| SrO | 1.15 | 0.020 |
| Al₂O₃ | 0.25 | 0.004 |
| Na₂O | 0.15 | 0.004 |
| Fe₂O₃ | 0.04 | 0.000 |
- Equivalent weight
- 179.08
- Fired weight
- 136.1
- Loss on ignition
- 24%
The equivalent weight is the grams of Colemanite (commercial) that hold 1.0 mole of flux. The fired weight is what is left of that after firing.
Hazards and safety
Hazards: Not classified (Etimine SDS); the natural ore contains 8–12% calcite and 6–8% clay, and CTM's SDS notes traces of arsenic sulphides; avoid breathing the dust.
Use it in a recipe
Add Colemanite (commercial) to a recipe in the Glazecalc calculator to see what it does to a glaze's unity formula.