Natroboltwoodite is a rare secondary uranium silicate mineral that forms as a result of the alteration of uraninite. It typically appears as fine, fibrous yellow acicular crusts or radiating aggregates in oxidized uranium deposits. Due to its radioactive and toxic nature, it is strictly a specimen for experienced mineral collectors who employ proper containment and safety protocols.
Is this natroboltwoodite?
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 natroboltwoodite with a known reference. Natroboltwoodite sits at Mohs 3.5-4, 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: earthy.
- 4Match the color rangeCompare against the expected color range: yellow, white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: fibrous, acicular, radiating clusters.
Often confused with
Natroboltwoodite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads earthy on Natroboltwoodite and pearly; radial aggregates vitreous to silky; dull to earthy in microcrystalline pseudomorphs on Boltwoodite.
How to tell apart: Streak differs, so Natroboltwoodite leaves white, Kasolite leaves pale yellow-brown; luster reads earthy on Natroboltwoodite and subadamantine to greasy, dull to earthy when massive on Kasolite.
How to tell apart: Natroboltwoodite is noticeably harder (Mohs 3.5-4 vs. 2.5); streak differs, so Natroboltwoodite leaves white, Uranophane leaves yellowish white; luster reads earthy on Natroboltwoodite and vitreous on Uranophane.
Often found alongside natroboltwoodite
Minerals reported to co-occur with natroboltwoodite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na(UO₂)(SiO₃OH)(H₂O)
- Mohs hardness
- 3.5-4
- Density
- 4.1 g/cm³
- Streak
- White
- Luster
- Earthy
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Fibrous, acicular, radiating clusters
- Cleavage
- Perfect
- Fluorescence
- Bright green under SW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidation zone mineral
Where rockhounds find natroboltwoodite
Classic worldwide localities
- Unspecifed arid regions of the former USSR (type locality)
Field-hunting tip
Where it forms: Oxidation zone mineral. If you start seeing uraninite, gummite, quartz in float, you are in the right ground. Typical habit: fibrous, acicular, radiating clusters. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify natroboltwoodite?+
Where is natroboltwoodite found?+
Is natroboltwoodite safe to handle?+
What rocks look like natroboltwoodite?+
What minerals are found with natroboltwoodite?+
What kind of rock does natroboltwoodite form in?+
What is natroboltwoodite used for?+
Find natroboltwoodite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
