Sanmartinite is a very rare zinc tungstate mineral that typically appears as yellow to yellowish-brown tabular crystals. It is primarily identified by its distinct adamantine luster and its association with hydrothermal vein deposits, occurring most notably in Argentina.
Is this sanmartinite?
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 sanmartinite with a known reference. Sanmartinite sits at Mohs 4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Sanmartinite leaves a yellowish-white streak.
- 3Read the lusterHold the specimen under a strong light. Sanmartinite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellowish-brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals.
Often confused with
Sanmartinite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Sanmartinite leaves yellowish-white, Wolframite leaves dark brown to black; luster reads adamantine on Sanmartinite and submetallic to metallic on Wolframite.
How to tell apart: Streak differs — Sanmartinite leaves yellowish-white, Scheelite leaves white; luster reads adamantine on Sanmartinite and vitreous on Scheelite.
Often found alongside sanmartinite
Minerals reported to co-occur with sanmartinite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- ZnWO₄
- Mohs hardness
- 4
- Density
- 6.57 g/cm³
- Colors
- Streak
- Yellowish-white
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals
- Cleavage
- Perfect On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Quartz Veins
- Typical price
- $100-500 per specimen
Where rockhounds find sanmartinite
Classic worldwide localities
- San Luis Province, Argentina
- La Rioja, Argentina
Field-hunting tip
Look in hydrothermal quartz veins country — that is the host setting where sanmartinite typically forms. If you start seeing quartz, muscovite, fluorite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find sanmartinite on the map
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