Norbergite is a member of the humite group typically found in contact-metamorphosed limestone or dolomitic marbles. It is most easily identified in the field by its distinct bright yellow fluorescence under shortwave ultraviolet light.
Is this norbergite?
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 norbergite with a known reference. Norbergite sits at Mohs 6-6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to resinous.
- 4Match the color rangeCompare against the expected color range: yellow, white, brown, red.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: granular, massive, or small stubby prismatic crystals.
Often confused with
Norbergite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside norbergite
Minerals reported to co-occur with norbergite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₃SiO₄F₂
- Mohs hardness
- 6-6.5
- Density
- 3.177 g/cm³
- Streak
- White
- Luster
- Vitreous to resinous
- Transparency
- Transparent to translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Granular, massive, or small stubby prismatic crystals
- Cleavage
- Distinct
- Fluorescence
- Bright yellow under SW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In contact metamorphic zones in limestones and dolostones into which plutonic rocks or pegmatites have introduced fluorine
Where rockhounds find norbergite
Classic worldwide localities
- Nicoll quarry, Franklin, Sussex Co., New Jersey, USA
- Edenville, Orange Co., and in the Balmat mines, St. Lawrence Co., New York, USA
- Piukkala, near Pargas, Finland
- Loch Ness, Inverness-shire, Scotland
- Monte Somma and Nocera, Campania, Italy
Field-hunting tip
Where it forms: In contact metamorphic zones in limestones and dolostones into which plutonic rocks or pegmatites have introduced fluorine. If you start seeing dolomite, calcite, tremolite in float, you are in the right ground. Typical habit: granular, massive, or small stubby prismatic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify norbergite?+
Where is norbergite found?+
What rocks look like norbergite?+
What minerals are found with norbergite?+
What kind of rock does norbergite form in?+
What is norbergite used for?+
Find norbergite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
