Ferrorosemaryite is a rare phosphate mineral primarily found within complex granite pegmatite systems. It typically occurs as small, dark brown to black tabular crystals and is most notable for being a specific iron-dominant member of the fillowite group.
Is this ferrorosemaryite?
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 ferrorosemaryite with a known reference. Ferrorosemaryite sits at Mohs 4-4.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Ferrorosemaryite leaves a yellow-brown streak.
- 3Read the lusterHold the specimen under a strong light. Ferrorosemaryite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: dark brown, black, yellow-brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, massive, granular.
Often confused with
Ferrorosemaryite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside ferrorosemaryite
Minerals reported to co-occur with ferrorosemaryite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- LiFe²⁺Al(PO₄)₂(OH)₂
- Mohs hardness
- 4-4.5
- Density
- 3.85 g/cm³
- Streak
- Yellow-brown
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Massive, Granular
- Cleavage
- Distinct On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
- Typical price
- $50-300 per specimen
Where rockhounds find ferrorosemaryite
Classic worldwide localities
- Tip Top mine, South Dakota, USA
- Braz, Brazil
Field-hunting tip
Look in granite pegmatites country — that is the host setting where ferrorosemaryite typically forms. If you start seeing quartz, muscovite, triplite in float, you are in the right ground. Field specimens usually show a tabular crystals, massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferrorosemaryite?+
Where is ferrorosemaryite found?+
How much is ferrorosemaryite worth?+
What rocks look like ferrorosemaryite?+
What minerals are found with ferrorosemaryite?+
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Find ferrorosemaryite on the map
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