Sekaninaite
A variety of Minerals
What is Sekaninaite?
Sekaninaite ((Fe,Mg)2Al4Si5O18) is a silicate mineral, the iron-rich analogue of cordierite. It was first described in 1968 for an occurrence in Dolní Bory, Vysočina Region, Moravia, Czech Republic, and is now known also from Ireland, Japan, and Sweden. It was named after a Czech mineralogist, Josef Sekanina (1901–1986). In Brockley on Rathlin Island, Ireland sekaninaite occurs in bauxitic clay within the contact aureole of a diabase intrusive plug.
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Sekaninaite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Sekaninaite Localities Map
See where Sekaninaite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Key Characteristics
Characteristics of Sekaninaite
Stanek and Miskovsky (1975) first identified and diagnosed sekaninaite as a new mineral in the cordierite series. They sampled the poorly developed crystals of the Dolni Bory region, Czechoslovakia, where specimen did not exceed 70 cm. Dolni Bory samples are very different from samples found in the Kuznetsk paralavas. They are very close analogues with respect to Mg/Fe ratios but vastly different a-, b- and c- parameters (Grapes, 2010). Grapes and colleagues calculated cell dimension to be a 17.230(5), b 9.835(3), c 9.314(3) A. The colour of sekaninaite is bright blue and distinctly pleochroic with X = colourless; Y = blue; Z = pale blue; absorption occurs in the sequence Y > Z > X. Sekaninaite has a hardness of 7-7.5; it cleaves imperfectly along {100} and exhibits parting on {001} (Fleischer, 1977). Majority of crystals show zonation (Fe increasing from core to rim). It common twinned on {110} and {310}, simulating hexagonal symmetry. Sekaninaite is classified under the space group Cccm; it is an orthorhombic crystal that is found in series with cordierite (Stanek, 1975).
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Quick Facts
Physical Properties
- Color
- grayish-blue to bluish-violet
- Hardness (Mohs)
- 7.5
Chemical Properties
- Chemical Formula
- (Fe,Mg)2Al3(AlSi5O18)
- Elements
- Al, Fe, Mg, O, Si
Also Known As
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Sekaninaite FAQs
How do I identify Sekaninaite?
Sekaninaite can be identified by its hardness of 7.5 on the Mohs scale, grayish-blue to bluish-violet color. Look for these key characteristics when examining specimens.
What color is Sekaninaite?
Sekaninaite typically appears in grayish-blue to bluish-violet. Color can vary depending on impurities and formation conditions.
How hard is Sekaninaite?
Sekaninaite has a hardness of 7.5 on the Mohs scale. This makes it a relatively hard mineral suitable for jewelry.
What is the characteristics of sekaninaite of Sekaninaite?
Stanek and Miskovsky (1975) first identified and diagnosed sekaninaite as a new mineral in the cordierite series. They sampled the poorly developed crystals of the Dolni Bory region, Czechoslovakia, where specimen did not exceed 70 cm. Dolni Bory samples are very different from samples found in the Kuznetsk paralavas. They are very close analogues with respect to Mg/Fe ratios but vastly different a-, b- and c- parameters (Grapes, 2010). Grapes and colleagues calculated cell dimension to be a 17.230(5), b 9.835(3), c 9.314(3) A. The colour of sekaninaite is bright blue and distinctly pleochroic with X = colourless; Y = blue; Z = pale blue; absorption occurs in the sequence Y > Z > X. Sekaninaite has a hardness of 7-7.5; it cleaves imperfectly along {100} and exhibits parting on {001} (Fleischer, 1977). Majority of crystals show zonation (Fe increasing from core to rim). It common twinned on {110} and {310}, simulating hexagonal symmetry. Sekaninaite is classified under the space group Cccm; it is an orthorhombic crystal that is found in series with cordierite (Stanek, 1975).
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