Cacoxenite (incl.)
Cacoxenite is a fairly common phosphate mineral that is usually found as minute, acicular, spherical radiating bundles or as golden to brownish yellow needle inclusions in Quartz and Amethyst. It is beautiful as bright golden yellow, chatoyant needle inclusions in Quartz cabochons. Cacoxenite is available as small mineral specimens but somewhat rare as a gemstone. The best material for Quartz/Cacoxenite cabochons is from Bahia and Minas Gerais, Brazil.
Cacoxenite is widespread in small amounts. In the Czech Republic, from the Hrbek mine, Svatá Dobrotivá (St. Benigna); at Trenice; from Zbirov; and at Cerhovice. In Germany, from the Eleonore and Rotläufchen mines, near Giessen, Hesse, and at Hiihnerkobel, near Zwiesel, Bavaria. In France, at Rochefort-en-Terre, Morbihan. From Shanagolden, County Limerick, Ireland. At Kiruna, Sweden. In the USA, from the Palermo #1 mine, near North Groton, Grafton County, New Hampshire; from Pennsylvania, at Hellertown, Northampton County, Moore’s Mill, Cumberland County, and Noble’s mine, Lancaster County On Indian Mountain, Cherokee County, Alabama, groups large for the species; in the Wilson Springs (Potash Sulphur Springs) mine, Garland County, from the Avant claim, about three km southwest of Shady, and at Three Oak Gap, Polk County, Arkansas; in the Vanleer mine, Iron City, Lawrence County, Tennessee; from the Palmetto mine, southwest of Bartow, Polk County, Florida.
| Category: |
Phosphate minerals |
| Chemical Formula: | Fe2+24Al(PO4)17O6(OH)12 · ~75(H2O) |
| Hydrated Iron Aluminum Phosphate Oxide Hydroxide | |
| Molecular Weight: | 4,481.51 gm |
| Composition: | Aluminum | 3.76 % | Al | 7.11 % | Al2O3 |
| Iron | 23.37 % | Fe | 30.06 % | FeO | |
| Phosphorus | 11.75 % | P | 26.92 % | P2O5 | |
| Hydrogen | 3.64 % | H | 32.56 % | H2O | |
| Oxygen | 57.48 % | O | |||
| 100.00 % | 100.00 % | = TOTAL OXIDE |
| Crystallography: | Hexagonal – Dihexagonal Dipyramidal |
| Crystal Habit: | Crystals, may be crudely hexagonal, acicular along [0001], typically in compact concentric spherical to radial aggregates, to 8 mm; in bundles, randomly fibrous; as coatings or an intergranular cement. |
| Twinning: | None |
| Cleavage: | None |
| Fracture: | Irregular/Uneven |
| Tenacity: | Brittle |
| Moh’s Hardness: | 3.0 – 4.0 |
| Density: | 2.20 – 2.60 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Other: | Readily soluble in acids. |
| Color: | Yellow to Brownish Yellow or Reddish Orange, Golden Yellow, deep Orange, rarely Greenish |
| Transparency: | Semi-Transparent to Translucent |
| Luster: | Silky |
| Refractive Index: | 1.575 – 1.656 Uniaxial ( + ) |
| Birefringence: | 0.060 |
| Dispersion: | None |
| Pleochroism: | Visible; 0 = pale yellow; E = canary-yellow to yellow-orange |
