Ewingite is a complex uranyl carbonate mineral currently recognized as the most structurally complex mineral known to science. It typically appears as tiny, bright yellow, platy crystals in uranium mine tailings and is highly sought after by advanced mineral collectors for its unique structural significance.
Is this ewingite?
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 ewingite with a known reference. Ewingite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Ewingite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Ewingite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, greenish-yellow.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: platy crystals, crusts.
Often confused with
Ewingite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Ewingite leaves yellow, Liebigite leaves pale yellow.
How to tell apart: Streak differs — Ewingite leaves yellow, Andersonite leaves white.
How to tell apart: Streak differs — Ewingite leaves yellow, Schröckingerite leaves pale yellow; luster reads vitreous on Ewingite and pearly on Schröckingerite.
Often found alongside ewingite
Minerals reported to co-occur with ewingite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₈Ca₈(UO₂)₂₄(CO₃)₃₀O₄(OH)₁₂·138H₂O
- Mohs hardness
- 2
- Density
- 2.8 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Tetragonal
- Crystal habit
- Platy Crystals, Crusts
- Cleavage
- None
- Fluorescence
- Strong Green Under UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Uranium-bearing Hydrothermal Veins
- Typical price
- $100-500 per specimen
Where rockhounds find ewingite
Classic worldwide localities
- Plavno mine, Czech Republic
Field-hunting tip
Look in uranium-bearing hydrothermal veins country — that is the host setting where ewingite typically forms. If you start seeing liebigite, andersonite, schröckingerite in float, you are in the right ground. Field specimens usually show a platy crystals, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find ewingite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
