Thadeuite is a very rare phosphate mineral found primarily in complex granite pegmatites. It typically occurs as small, yellow-orange, prismatic crystals and is visually similar to members of the apatite group, often requiring chemical analysis for definitive identification.
Is this thadeuite?
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 thadeuite with a known reference. Thadeuite sits at Mohs <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: vitreous.
- 4Match the color rangeCompare against the expected color range: yellow orange.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: cleaveable, granular.
Often confused with
Thadeuite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside thadeuite
Minerals reported to co-occur with thadeuite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaMg₃(PO₄)₂(OH,F)₂
- Mohs hardness
- <4
- Density
- 3.25 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Cleaveable, granular
- Cleavage
- On {010}, very good; another perpendicular
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A very rare primary mineral in the margins of hydrothermal veins, formed between 230° –360°C and 100–1000 bars
Where rockhounds find thadeuite
Classic worldwide localities
- Panasqueira Sn–W deposit, Portugal
Field-hunting tip
Where it forms: A very rare primary mineral in the margins of hydrothermal veins, formed between 230° –360°C and 100–1000 bars. If you start seeing fluorapatite, wolfeite, topaz in float, you are in the right ground. Typical habit: cleaveable, granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify thadeuite?+
Where is thadeuite found?+
What rocks look like thadeuite?+
What minerals are found with thadeuite?+
What kind of rock does thadeuite form in?+
What is thadeuite used for?+
Find thadeuite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
