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 greenish to brownish streak.
- 3Read the lusterHold the specimen under a strong light. Ferrorosemaryite typically shows a resinous 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.
How to tell apart: Streak differs, so Ferrorosemaryite leaves greenish to brownish, Fillowite leaves white; luster reads resinous on Ferrorosemaryite and greasy on Fillowite.
How to tell apart: Streak differs, so Ferrorosemaryite leaves greenish to brownish, Triplite leaves white; luster reads resinous on Ferrorosemaryite and vitreous on Triplite.
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
- Greenish to Brownish
- Luster
- Resinous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Massive, Granular
- Cleavage
- Distinct On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
Where rockhounds find ferrorosemaryite
Classic worldwide localities
- Rubindi-Kabilizi pegmatite, south of the Rubindi river, 50 km west of Kigali, Rwanda
Field-hunting tip
Look in granite pegmatites country, 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?+
What rocks look like ferrorosemaryite?+
What minerals are found with ferrorosemaryite?+
What kind of rock does ferrorosemaryite form in?+
What is ferrorosemaryite used for?+
Find ferrorosemaryite on the map
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