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. Andymcdonaldite leaves a pale yellow-brown streak.
- 3Read the lusterHold the specimen under a strong light. Andymcdonaldite typically shows a earthy luster.
- 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
Look in metamorphosed limestone country, the host setting where andymcdonaldite typically forms. If you start seeing sanbornite, walstromite, quartz in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify andymcdonaldite?+
Where is andymcdonaldite found?+
What rocks look like andymcdonaldite?+
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Find andymcdonaldite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
