Dellagiustaite is a rare member of the spinel group characterized by its vanadium-rich composition. It typically occurs as minute octahedral crystals within volcanic xenoliths and was only recently established as a distinct species.
Is this dellagiustaite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch dellagiustaite with a known reference. Dellagiustaite sits at Mohs 5.5-6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Dellagiustaite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Dellagiustaite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: cubic. Typical habit: octahedral crystals.
Often confused with
Dellagiustaite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Spinel is the harder of the two (Mohs 8 vs. 5.5-6); streak differs, so Dellagiustaite leaves black, Spinel leaves white; luster reads submetallic on Dellagiustaite and vitreous on Spinel.
How to tell apart: Luster reads submetallic on Dellagiustaite and metallic on Magnetite.
How to tell apart: Streak differs, so Dellagiustaite leaves black, Chromite leaves dark brown.
Often found alongside dellagiustaite
Minerals reported to co-occur with dellagiustaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- VAl₂O₄
- Mohs hardness
- 5.5-6
- Density
- 4.86 g/cm³
- Colors
- Streak
- Black
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Octahedral Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Xenoliths in Volcanic Rocks
- Typical price
- $50-500 depending on specimen quality
Where rockhounds find dellagiustaite
Classic worldwide localities
- Kozakov, Czech Republic
Field-hunting tip
Look in xenoliths in volcanic rocks country, the host setting where dellagiustaite typically forms. If you start seeing corundum, spinel, rutile in float, you are in the right ground. Field specimens usually show a octahedral crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find dellagiustaite on the map
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