Datolite nodules are prized by collectors for their smooth, porcelain-like appearance and potential for high-quality lapidary work. They are most famous from the copper mines of Michigan's Keweenaw Peninsula, where they often exhibit varied internal banding and colors. Collectors should look for a waxy luster and test for strong yellow-green fluorescence under ultraviolet light.
Is this datolite nodule?
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 datolite nodule with a known reference. Datolite Nodule sits at Mohs 5-5.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Datolite Nodule leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Datolite Nodule typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, yellow, green, red, brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: nodular.
Often confused with
Datolite Nodule vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside datolite nodule
Minerals reported to co-occur with datolite nodule. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaBSiO₄(OH)
- Mohs hardness
- 5-5.5
- Density
- 2.9-3.0 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Nodular
- Cleavage
- None
- Fluorescence
- Often Bright Yellow-green Under SW UV
- Rarity
- Uncommon
- Uses
- Collector, Lapidary
- Host rock
- Hydrothermal Veins, Basalt, Contact Metamorphic Rocks
- Typical price
- $10-150 depending on size and color quality
Where rockhounds find datolite nodule
Classic worldwide localities
- Keweenaw Peninsula, Michigan, USA
- Dalnegorsk, Russia
- Hartford Basin, Connecticut, USA
- Charcas, Mexico
Field-hunting tip
Look in hydrothermal veins, basalt, contact metamorphic rocks country — that is the host setting where datolite nodule typically forms. If you start seeing calcite, danburite, apophyllite in float, you are in the right ground. Field specimens usually show a nodular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find datolite nodule on the map
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