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 6.5-7, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 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: Streak differs, so Dellagiustaite leaves black, Spinel leaves white; luster reads metallic on Dellagiustaite and vitreous, splendent to dull on Spinel.
How to tell apart: Dellagiustaite is noticeably harder (Mohs 6.5-7 vs. 5.5); streak differs, so Dellagiustaite leaves black, Chromite leaves 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
- 6.5-7
- Density
- 4.6 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Octahedral crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- xenoliths in volcanic rocks
Where rockhounds find dellagiustaite
Classic worldwide localities
- Sierra de Comechingones, San Luis, Argentina (type locality)
- Mt. Carmel, northern Israel
Field-hunting tip
Where it forms: xenoliths in volcanic rocks. If you start seeing hibonite, grossite, gehlenite in float, you are in the right ground. Typical habit: octahedral crystals. 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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