Dickthomssenite is a very rare magnesium vanadate mineral that typically forms as small, tabular pale golden brown 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 2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: light golden brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: microscopic crystals, platy, radial.
Often confused with
Dickthomssenite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Dickthomssenite leaves white, Sherwoodite leaves pale blue.
How to tell apart: Streak differs, so Dickthomssenite leaves white, Metavanuralite leaves light yellow; luster reads vitreous on Dickthomssenite and pearly on Metavanuralite.
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
- 2.5
- Density
- 1.96-2.09 g/cm³
- Colors
- Light golden brown
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Microscopic crystals, platy, radial
- Cleavage
- Perfect on {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In the oxidized zone of a sandstone U–V deposit
Where rockhounds find dickthomssenite
Classic worldwide localities
- Firefly-Pigmay U–V mine, 16 km east of La Sal, San Juan Co., Utah, USA
Field-hunting tip
Where it forms: In the oxidized zone of a sandstone U–V deposit. If you start seeing pascoite, sherwoodite, selenium in float, you are in the right ground. Typical habit: microscopic crystals, platy, radial. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify dickthomssenite?+
Where is dickthomssenite found?+
Is dickthomssenite safe to handle?+
What rocks look like dickthomssenite?+
What minerals are found with dickthomssenite?+
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Find dickthomssenite on the map
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