Ordoñezite is a very rare zinc antimonate mineral that typically occurs as small, sharp, brown tetragonal crystals. It is most frequently found in hydrothermal vein deposits associated with tin and silver mining districts, particularly in South America. Collectors prize it for its high specific gravity and its relationship to the tapiolite mineral group.
Is this ordoñezite?
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 ordoñezite with a known reference. Ordoñezite sits at Mohs 6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: greenish gray.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: colorless, yellow green, light brown, dark brown, olive green.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: prismatic to tabular crystals.
Often confused with
Ordoñezite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Ordoñezite leaves greenish gray, Cassiterite leaves white, pale brown, pale gray.
How to tell apart: Ordoñezite is noticeably harder (Mohs 6.5 vs. 5.5); streak differs, so Ordoñezite leaves greenish gray, Stibiotantalite leaves pale yellow to yellow-brown; luster reads adamantine on Ordoñezite and resinous to adamantine on Stibiotantalite.
Often found alongside ordoñezite
Minerals reported to co-occur with ordoñezite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- ZnSb₂O₆
- Mohs hardness
- 6.5
- Density
- 6.635 g/cm³
- Streak
- Greenish gray
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Tetragonal
- Crystal habit
- Prismatic to tabular crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Deposited at a late stage with pneumatolytic tin ore in fractures in rhyolite (Santín mine, Mexico)
Where rockhounds find ordoñezite
Classic worldwide localities
- Santín mine, about eight km from Santa Caterina, Guanajuato, and from El Antimonio, 27 km southwest of Agua Prieta, Sonora, Mexico
Field-hunting tip
Where it forms: Deposited at a late stage with pneumatolytic tin ore in fractures in rhyolite (Santín mine, Mexico). If you start seeing cassiterite, hematite, quartz in float, you are in the right ground. Typical habit: prismatic to tabular crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ordoñezite?+
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What rocks look like ordoñezite?+
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Find ordoñezite on the map
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