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Dumortierita
Main Deposits
Brazil (main source), France, Madagascar, Namibia, United States (Nevada), and Peru.
Description and Characteristics
Dumortierite is an aluminum borosilicate that typically forms in aluminum-rich metamorphic rocks and granitic pegmatites. While it can occur as rare prismatic crystals, it is most commonly found in massive, fibrous, or columnar aggregates. It is distinguished by its intense blue color and great toughness. It was discovered in 1881 in Chaponost (France) and named after the French paleontologist Eugène Dumortier. Due to its color, it is often confused with sodalite or lapis lazuli, but it lacks the white calcite or golden pyrite inclusions of the latter. It is a highly valued stone for carving ornamental objects and cabochons because of its ability to take an exceptional polish.
| Chemical Formula | $$Al7BO3(SiO4)3O3$$ |
|---|---|
| Luster | Vitreous to dull |
| Streak | White |
| Fracture | Conchoidal to irregular |
| Cleavage | Good (in one direction) |
| Hardness | 7 Mohs |
| Crystal System | Orthorhombic |
Did you know...?
One of the most spectacular forms of this mineral occurs when dumortierite grows inside clear quartz crystals, creating inclusions that look like tiny blue "fireworks" or "urchins" trapped in ice; these specimens are extremely rare and highly sought after. In addition to its ornamental use, dumortierite is used industrially in the manufacture of high-quality porcelain and spark plugs due to its resistance to thermal expansion and high temperatures.
New-Age Properties
Dumortierite is known as the stone of "patience" and "mental order." It helps organize thoughts and maintain discipline in study or work, facilitating the retention of information. Spiritually, it opens communication with higher guidance and helps in understanding life's karmic processes. It is an excellent stone for those who feel they have no control over their destiny, as it boosts self-confidence and the ability to stand on one's own. Emotionally, it calms irritability and stress, helping to overcome crises with a positive and centered attitude.