Julgoldite-(Mg) is a rare member of the pumpellyite group found in specialized metamorphic environments. Collectors should look for dark, tabular crystals or radiating sprays typically occurring in association with manganese-rich mineral suites.
Is this julgoldite-(mg)?
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-(mg) with a known reference. Julgoldite-(Mg) 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. Julgoldite-(Mg) leaves a greenish olive streak.
- 3Read the lusterHold the specimen under a strong light. Julgoldite-(Mg) 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.
Often found alongside julgoldite-(mg)
Minerals reported to co-occur with julgoldite-(mg). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂MgFe²⁺Fe³⁺(Si₂O₇)(SiO₄)(OH)₂·H₂O
- Mohs hardness
- 4.5
- Colors
- Streak
- Greenish Olive
- Luster
- Vitreous
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Radiating Aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphic Manganese Deposits
Where rockhounds find julgoldite-(mg)
Classic worldwide localities
- Långban, Sweden
- Sahara, Morocco
Field-hunting tip
Look in metamorphic manganese deposits country, the host setting where julgoldite-(mg) typically forms. If you start seeing hematite, calcite, andradite in float, you are in the right ground. Field specimens usually show a tabular crystals, radiating aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify julgoldite-(mg)?+
Where is julgoldite-(mg) found?+
What minerals are found with julgoldite-(mg)?+
What kind of rock does julgoldite-(mg) form in?+
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Find julgoldite-(mg) on the map
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