Ruifrancoite is a rare phosphate mineral primarily found in granitic pegmatites. It typically occurs as small tabular crystals associated with other phosphate minerals, often requiring microscopic examination for positive identification due to its similarity to other members of the fillowite group.
Is this ruifrancoite?
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 ruifrancoite with a known reference. Ruifrancoite 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. Ruifrancoite leaves a orange-brown streak.
- 3Read the lusterHold the specimen under a strong light. Ruifrancoite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellow-brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals.
Often confused with
Ruifrancoite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Ruifrancoite leaves orange-brown, Fillowite leaves white; luster reads vitreous on Ruifrancoite and greasy on Fillowite.
How to tell apart: Streak differs, so Ruifrancoite leaves orange-brown, Johnsomervilleite leaves pale brown.
Often found alongside ruifrancoite
Minerals reported to co-occur with ruifrancoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂(☐,Mn)₂(Fe³⁺,Mn,Mg)₄Be₄(PO₄)₆(OH)₆·4H₂O
- Mohs hardness
- 4
- Density
- 2.88 g/cm³
- Colors
- Streak
- Orange-brown
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals
- Cleavage
- Perfect On {100}, Good On {010} (by Analogy to Other Roscherite-group Minerals)
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
Where rockhounds find ruifrancoite
Classic worldwide localities
- Sapucaia mine, Minas Gerais, Brazil
Field-hunting tip
Look in granite pegmatites country, the host setting where ruifrancoite typically forms. If you start seeing quartz, muscovite, albite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ruifrancoite?+
Where is ruifrancoite found?+
What rocks look like ruifrancoite?+
What minerals are found with ruifrancoite?+
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Find ruifrancoite on the map
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