Dickthomssenite is a very rare magnesium vanadate mineral that typically forms as small, tabular yellow crystals. It is primarily found as a secondary mineral in oxidized uranium-vanadium deposits in the Colorado Plateau of Utah. Collectors value it for its limited occurrence and delicate crystalline habit.
Is this dickthomssenite?
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 dickthomssenite with a known reference. Dickthomssenite 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. Dickthomssenite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Dickthomssenite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellow-orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, radiating aggregates.
Often confused with
Dickthomssenite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside dickthomssenite
Minerals reported to co-occur with dickthomssenite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MgV₂O₆·7H₂O
- Mohs hardness
- 2
- Density
- 4.26 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Radiating Aggregates
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Sandstone Hosted Uranium-vanadium Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find dickthomssenite
Classic worldwide localities
- Thompson mine, Utah, USA
- La Sal mine, Utah, USA
Field-hunting tip
Look in sandstone hosted uranium-vanadium deposits country — that is the host setting where dickthomssenite typically forms. If you start seeing gypsum, sherwoodite, metavanuralite in float, you are in the right ground. Field specimens usually show a tabular crystals, radiating aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find dickthomssenite on the map
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