Julgoldite-(Fe2+) is a rare member of the pumpellyite group, typically occurring as dark, small crystals in metamorphic environments. It is best identified by its deep black color and association with iron-rich mineral assemblages in specific manganese-bearing deposits. Collectors typically acquire this mineral as rare, micro-crystalline specimens from classic Swedish or North American localities.
Is this julgoldite-(fe2+)?
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 julgoldite-(fe2+) with a known reference. Julgoldite-(Fe2+) sits at Mohs 5.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Julgoldite-(Fe2+) leaves a brown streak.
- 3Read the lusterHold the specimen under a strong light. Julgoldite-(Fe2+) typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: black, brownish-black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, radiating aggregates, massive.
Often confused with
Julgoldite-(Fe2+) vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside julgoldite-(fe2+)
Minerals reported to co-occur with julgoldite-(fe2+). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂Fe²⁺(Fe³⁺,Al,Mg)(Si₂O₇)(SiO₄)(OH)₂·H₂O
- Mohs hardness
- 5.5
- Density
- 3.55 g/cm³
- Colors
- Streak
- Brown
- Luster
- Vitreous
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Radiating Aggregates, Massive
- Cleavage
- Poor
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphic Iron-manganese Deposits
- Typical price
- $20-150 for micromounts or small cabinet specimens
Where rockhounds find julgoldite-(fe2+)
Classic worldwide localities
- Långban, Sweden
- Hibbing, Minnesota, USA
- Guanajuato, Mexico
Field-hunting tip
Look in metamorphic iron-manganese deposits country — that is the host setting where julgoldite-(fe2+) typically forms. If you start seeing andradite, hematite, calcite in float, you are in the right ground. Field specimens usually show a tabular crystals, radiating aggregates, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify julgoldite-(fe2+)?+
Where is julgoldite-(fe2+) found?+
How much is julgoldite-(fe2+) worth?+
What rocks look like julgoldite-(fe2+)?+
What minerals are found with julgoldite-(fe2+)?+
What kind of rock does julgoldite-(fe2+) form in?+
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Find julgoldite-(fe2+) on the map
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