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Diaspore is one of the three component minerals of the economically important aluminum ore Bauxite. Though most forms of this mineral are not of much interest to the collector, large exceptional crystals unlike any others were found in Turkey in the 1950's in a commercial Bauxite deposit. This deposit has become the source of mining operations producing exceptional specimens and gem-grade crystals that are cut into gemstones. The company operating the gem Diaspore mine was previously called Zultanite Gems LLC, and they had given this form of Diaspore the trade name " Zultanite". They have recently dropped this name in favor of a new trade name, Csarite. For additional information, see the gemstone section on Diaspore. |
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Chemical Formula |
AlO(OH) |
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Composition |
Basic aluminum oxide
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Color |
Colorless, white, gray, green, light olive-green, light yellowish-green, yellow, light brown, light orange, pink, purple, and red. Diaspore can exhibit a color changing property where under natural or fluorescent lighting it has a light yellowish-green color, and in incandescent or candlelight it has a light pinkish-orange to raspberry-red color. |
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Streak |
White |
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Hardness |
6.5 - 7 |
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Crystal System |
Orthorhombic |
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Crystal Forms
and Aggregates |
In small thin prismatic and tabular crystal plates and bladed aggregates. Also foliated, scaly, micaceous, grainy, nodular, radiating, acicular, stalactitic, and massive. Crystals from Turkey are unique in habit, being relatively large and
usually thin prismatic or columnar, sometimes elongated, and
often twinned in interesting v-shaped (and occasionally even w-shaped) twins. Diaspore crystals are often striated. |
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Transparency |
Transparent to translucent |
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Specific Gravity |
3.3 - 3.5 |
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Luster |
Vitreous, pearly |
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Cleavage |
1,2;2,1 |
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Fracture |
Conchoidal to uneven |
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Tenacity |
Brittle |
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In Group |
Oxides; Hydroxides |
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Striking Features |
Crystal formations, occurences, and hardness |
| Environment |
As a secondary mineral forming in the weathered surface zones in
clay deposits and limestones, in metamorphic marbles, and nepheline syenite pegmatites.
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| Rock Type |
Igneous, Sedimentary, Metamorphic |
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Popularity (1-4)
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3 |
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Prevalence (1-3)
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2 |
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Demand (1-3) |
1 |
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- Dark, purple, chromium-rich variety of Diaspore.
- New trade name given to the transparent, gemmy variety of Diaspore from Turkey, as a substitute for the name Zultanite.
- Manganese-rich, pink variety of Diaspore.
- Trade name given to the transparent, gemmy variety of Diaspore from Turkey. This name was officially abandoned in 2012 by Murat Akgun, the original promoter of the name Zultanite.
An explanation of the dropping of the name Zultanite in favor of "Gem Diaspore" is provided on the website www.zultanite.com, as follows:
"Mr. Murat Akgun, President of MML and the person who dedicated decades of his life to bringing the spectacular Turkish diaspore to its so well deserved worldwide fame and acclamation as 'Zultanite', decided that the promotion of this rare and unique gem will be better served under its genuine mineralogical name, rather than constriction by the bounds of a trademark. Mr. Akgun feels that branding will never actually permit to entirely set free the whole beauty and magic of this national treasure."
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Diaspore, being a component of Bauxite, is an important ore of aluminum. Crystallized Diaspore specimens are highly desired by mineral collectors, especially those from Turkey. The transparent, color-changing Diaspore gem often promoted by the name Zultanite is used as a gemstone.
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The premier Diaspore locality producing the largest and most outstanding crystals is in Turkey, near Pinarcik, in Mugla. Small green and purple Diaspore crystals come from the Saga 1 Quarry, Mørje, Telemark, Norway. A dark chromium-rich Diaspore associated with Uvarovite comes from Russia at the Saranovskii Mine in Sarany, Ural Mountains; and a manganese-rich pink and reddish form comes from the Kalahari manganese fields of South Africa at the Wessels Mine in Hotazel and the N'Chwaning Mines in Kuruman. In the U.S., fine crystallized plates came from the Emery deposits in Chester, Hampden Co., Massachusetts.
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Spodumene - Generally occurs in granite pegmatites, whereas large Diaspore crystals are found in other environments.
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