Boracite
Mg3B7O13ClIMA symbol: Bocgrandfathered
Boracite is a borate mineral with the formula Mg3B7O13Cl, crystallizing in the orthorhombic system. It has a Mohs hardness of 7, typically white, gray, green or yellow in color, with an adamantine or vitreous luster, a specific gravity of 2.9-3. Its streak is white.
Photos
Crystallography
| Crystal system | orthorhombic crystal systemWikidata (CC0) |
|---|---|
| Space group | P c a 21 |
| Cell (Å, °) | a = 8.5496, b = 8.5496, c = 12.091; α = 90, β = 90, γ = 90 |
| Cell volume | 883.8 ų, Z = 4 |
| Axial ratios | 1.0000:1:1.4142calculated from COD 5000209 |
| Source structure | COD 5000209 (Solid State Communications, 1972) — 1 of 7 structures |
Powder X-ray diffraction (calculated)
| d (Å) | 3.023 | 3.49 | 2.044 | 2.044 | 2.044 | 3.023 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 77.8 | 55.3 | 55.3 | 55 | 50.6 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 5000209; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 2.946 g/cm³calculated from COD 5000209 |
|---|---|
| Hardness (Mohs) | 7single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Specific gravity | 2.9-3 g/cm3corroboratedDana, System of Mineralogy, 6th ed. (1892) |
| Color | gray, green, white, yellowsingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Streak | whitesingle sourceWikidata (CC0) whitesingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Luster | adamantine, vitreoussingle sourceDana, System of Mineralogy, 6th ed. (1892) |
Chemistry (calculated)
| Molecular weight | 392.04 g/molcalculated from the IMA formula |
|---|---|
| Composition (wt%) | Mg 18.6%, B 19.3%, O 53.05%, Cl 9.04% |
Classification
| Nickel-Strunz (10th) | 6.GA.05Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 6.GA.05Wikidata (CC0) |