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, 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.
More datolite nodule photos
Common questions
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Find datolite nodule on the map
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