Ilvaite is a striking, iron-rich silicate typically found in black, vertically striated prismatic crystals. It is most frequently encountered in contact metamorphic zones known as skarns, where it forms in association with other calc-silicate minerals. Collectors often prize it for the sharp, well-defined crystal habits that can sometimes form large, impressive clusters.
Is this ilvaite?
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 ilvaite with a known reference. Ilvaite 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. Ilvaite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Ilvaite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: black, brownish-black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic, striated, columnar.
Often confused with
Ilvaite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Tourmaline is the harder of the two (Mohs 7-7.5 vs. 5.5-6); streak differs, so Ilvaite leaves black, Tourmaline leaves white; luster reads submetallic on Ilvaite and vitreous on Tourmaline.
How to tell apart: Streak differs, so Ilvaite leaves black, Arfvedsonite leaves grey to bluish-grey; luster reads submetallic on Ilvaite and vitreous on Arfvedsonite.
Often found alongside ilvaite
Minerals reported to co-occur with ilvaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaFe²⁺₂Fe³⁺(Si₂O₇)O(OH)
- Mohs hardness
- 5.5-6
- Density
- 3.8-4.1 g/cm³
- Colors
- Streak
- Black
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic, Striated, Columnar
- Cleavage
- Poor
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Contact Metamorphic Skarns
- Typical price
- $10-100 per specimen
Where rockhounds find ilvaite
Classic worldwide localities
- Elba, Italy
- Seriphos, Greece
- Skarn areas in Norway
- Idaho, USA
- British Columbia, Canada
Field-hunting tip
Look in contact metamorphic skarns country, the host setting where ilvaite typically forms. If you start seeing calcite, quartz, garnet in float, you are in the right ground. Field specimens usually show a prismatic, striated, columnar habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find ilvaite on the map
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