Kummerite is an extremely rare, purplish-pink variety of corundum specifically associated with the Franklin mining district in New Jersey. Collectors prize it for its unique locality-based color characteristics and its status as one of the few corundum occurrences in a metamorphosed zinc-iron-manganese deposit.
Is this kummerite?
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 kummerite with a known reference. Kummerite sits at Mohs 9, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Kummerite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Kummerite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: pink, violet, lavender.
- 5Look at form & habitCrystal system: trigonal. Typical habit: prismatic crystals.
Often confused with
Kummerite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside kummerite
Minerals reported to co-occur with kummerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Al₂O₃
- Mohs hardness
- 9
- Density
- 4.0 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Prismatic Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Gemstone, Collector
- Host rock
- Metamorphic Rocks
- Typical price
- $100-500 per carat
Where rockhounds find kummerite
Classic worldwide localities
- Franklin, New Jersey, USA
Field-hunting tip
Look in metamorphic rocks country, the host setting where kummerite typically forms. If you start seeing gahnite, calcite, willemite in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify kummerite?+
Where is kummerite found?+
How much is kummerite worth?+
What rocks look like kummerite?+
What minerals are found with kummerite?+
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Find kummerite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
