Fingerite is an extremely rare copper vanadate mineral discovered in the volcanic fumaroles of Izalco, El Salvador. It is typically found as small, black tabular crystals that are highly soluble in water, making it a challenging mineral to preserve in collections.
Is this fingerite?
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 fingerite with a known reference. Fingerite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: dark reddish brown.
- 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: triclinic. Typical habit: tabular crystals.
Often confused with
Fingerite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Fingerite leaves dark reddish brown, Vanadinite leaves white to pale red or pale yellow; luster reads metallic on Fingerite and subresinous to subadamantine on Vanadinite.
How to tell apart: Streak differs, so Fingerite leaves dark reddish brown, Cuprite leaves brownish red, shining; luster reads metallic on Fingerite and adamantine to submetallic, earthy on Cuprite.
Often found alongside fingerite
Minerals reported to co-occur with fingerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₁₁O₂(VO₄)₆
- Mohs hardness
- 3
- Density
- 4.776 g/cm³
- Colors
- Streak
- Dark reddish brown
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Triclinic
- Crystal habit
- Tabular crystals
- Cleavage
- Good on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare component of vanadium-bearing sublimates in fumaroles on a basaltic volcanic cone, formed between 100°C and 200°C
Where rockhounds find fingerite
Classic worldwide localities
- Izalco volcano, El Salvador
Field-hunting tip
Where it forms: A rare component of vanadium-bearing sublimates in fumaroles on a basaltic volcanic cone, formed between 100°C and 200°C. If you start seeing thenardite, euchlorine, stoiberite in float, you are in the right ground. Typical habit: tabular crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify fingerite?+
Where is fingerite found?+
Is fingerite safe to handle?+
What rocks look like fingerite?+
What minerals are found with fingerite?+
What kind of rock does fingerite form in?+
What is fingerite used for?+
Find fingerite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
