Santafeite is a complex rare arsenate mineral that occurs as small, dark, platy crystals or thin crusts in oxidized manganese deposits. It is primarily identified by its association with vanadium-rich mineralization and is mainly sought after by advanced mineral collectors for its complexity.
Is this santafeite?
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 santafeite with a known reference. Santafeite 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: brown.
- 3Read the lusterHold the specimen under a strong light. Luster: subadamantine.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular, encrustations.
Often confused with
Santafeite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Hausmannite is the harder of the two (Mohs 5.5 vs. 3); streak differs, so Santafeite leaves brown, Hausmannite leaves dark reddish brown; luster reads subadamantine on Santafeite and submetallic on Hausmannite.
How to tell apart: Psilomelane is the harder of the two (Mohs 5-6 vs. 3); streak differs, so Santafeite leaves brown, Psilomelane leaves brownish black; luster reads subadamantine on Santafeite and submetallic on Psilomelane.
Often found alongside santafeite
Minerals reported to co-occur with santafeite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ca,Sr,Na)₃(Mn,Fe)₂Mn₂(VO₄)₄(OH,O)₅·2H₂O
- Mohs hardness
- 3
- Density
- 3.379 g/cm³
- Colors
- Streak
- Brown
- Luster
- Subadamantine
- Transparency
- Opaque, translucent in thin fragments
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular, encrustations
- Cleavage
- {010}, perfect; {110}, distinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Rarely incrusting fractures in limestone (Grants district, New Mexico, USA) and in sandstone (Monument No. 1 mine, Arizona, USA) in Colorado Plateau-type U–V deposits
Where rockhounds find santafeite
Classic worldwide localities
- An unnamed uranium prospect about 20 km north of Grants, McKinley Co., New Mexico, USA
- Monument No. 1 mine, Monument Valley, Navajo Co., Arizona, USA
Field-hunting tip
Where it forms: Rarely incrusting fractures in limestone (Grants district, New Mexico, USA) and in sandstone (Monument No. 1 mine, Arizona, USA) in Colorado Plateau-type U–V deposits. If you start seeing calcite, cuprosklodowskite, carnotite in float, you are in the right ground. Typical habit: acicular, encrustations. Train your eye for that shape before scanning the outcrop.
Common questions
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Find santafeite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
