Ferroericssonite is a rare barium-iron silicate found in specific alkaline pegmatitic environments. It typically forms thin, dark, brittle platy crystals that are easily confused with related minerals of the bafertisite group.
Is this ferroericssonite?
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 ferroericssonite with a known reference. Ferroericssonite sits at Mohs ~4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: brown.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: dark reddish brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, platy aggregates.
Often confused with
Ferroericssonite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Ferroericssonite leaves brown, Bafertisite leaves white.
How to tell apart: Streak differs, so Ferroericssonite leaves brown, Ericssonite leaves rich brown; luster reads vitreous on Ferroericssonite and submetallic on Ericssonite.
Often found alongside ferroericssonite
Minerals reported to co-occur with ferroericssonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- BaFe₂Fe⁺³O(Si₂O₇)(OH)
- Mohs hardness
- ~4.5
- Density
- 4.413-4.445 g/cm³
- Colors
- Streak
- Brown
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular crystals, platy aggregates
- Cleavage
- Perfect on {100}; good on {011}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Along cleavage planes of altered gillespite in quartz-sanbornite veins
Where rockhounds find ferroericssonite
Classic worldwide localities
- Esquire 7 and 8 claims, along Big Creek, eastern Fresno County, and at Trumbull Peak, Mariposa County, California, USA
Field-hunting tip
Where it forms: Along cleavage planes of altered gillespite in quartz-sanbornite veins. If you start seeing anandite, bazirite, celsian in float, you are in the right ground. Typical habit: tabular crystals, platy aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferroericssonite?+
Where is ferroericssonite found?+
What rocks look like ferroericssonite?+
What minerals are found with ferroericssonite?+
What kind of rock does ferroericssonite form in?+
What is ferroericssonite used for?+
Find ferroericssonite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
