Andymcdonaldite is a rare iron tellurate. It occurs in au-, Te-, and Bi-rich jasperoid. It was first described from Wildcat prospect, northwest part of the Detroit District, Juab Co., Utah, USA.
Is this andymcdonaldite?
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 andymcdonaldite with a known reference. Andymcdonaldite sits at Mohs 4-4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale yellow-brown.
- 3Read the lusterHold the specimen under a strong light. Luster: earthy.
- 4Match the color rangeCompare against the expected color range: yellow-brown, brownish black.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: prismatic crystals.
Often confused with
Andymcdonaldite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Andymcdonaldite leaves pale yellow-brown, Edingtonite leaves white; luster reads earthy on Andymcdonaldite and vitreous on Edingtonite.
How to tell apart: Streak differs, so Andymcdonaldite leaves pale yellow-brown, Thomsonite leaves white; luster reads earthy on Andymcdonaldite and vitreous on Thomsonite.
Often found alongside andymcdonaldite
Minerals reported to co-occur with andymcdonaldite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe₂TeO₆
- Mohs hardness
- 4-4.5
- Density
- 5.91 g/cm³
- Streak
- Pale yellow-brown
- Luster
- Earthy
- Transparency
- Opaque
- Crystal system
- Tetragonal
- Crystal habit
- Prismatic crystals
- Cleavage
- Good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- metamorphosed limestone
Where rockhounds find andymcdonaldite
Classic worldwide localities
- Big Creek, Fresno County, California, USA
Field-hunting tip
Where it forms: metamorphosed limestone. If you start seeing sanbornite, walstromite, quartz in float, you are in the right ground. Typical habit: prismatic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify andymcdonaldite?+
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What rocks look like andymcdonaldite?+
What minerals are found with andymcdonaldite?+
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Find andymcdonaldite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
