Heliodor (Beryl)
Heliodor (or Golden Beryl) is the color that is yellow associated with the Beryl household of minerals which includes Aquamarine (blue), Bixbite (red), Emerald (green), Goshenite (colorless), Heliodor (yellow), Morganite (pink) and recently, Pezzottaite (pink and red). Heliodor gets its yellow color from traces of ferric iron included with the Beryl that is the fundamental formula. Large, clean crystals are available from areas that are few. Minas Gerais, Brazil is amongst the resources of Golden Beryl crystals.
| Category: | Cyclosilicate |
| Formula: | Be3Al2(SiO3)6 |
| Beryllium Aluminum Metasilicate | |
| Crystallography: | Hexagonal – Dihexagonal Dipyramidal |
| Crystal Habit: | Crystals are prismatic in tabular; may be complexly terminated by pyramids, to 18 m and 180 t. Also radial, trapiche, columnar; granular to compact. |
| Twinning: | Rarely |
| Cleavage: | [0001] Imperfect |
| Fracture: | Conchoidal to Uneven |
| Tenacity: | Brittle |
| Hardness (Mohs): | 7.5 – 8.0 |
| Hardness (Vickers): | VHN200=1239 – 1467 kg/mm2 |
| Density: | 2.63 – 2.92 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Color: | Pale Yellow, Yellow, Golden Yellow |
| Transparency: | Transparent to Translucent |
| Luster: | Vitreous (glassy) |
| Refractive Index: | 1.567 – 1.572 Uniaxial ( – ) |
| Birefringence: | 0.005- 0.007 |
| Dispersion: | 0.014 (low) |
| Pleochroism: | n/a |
