Datolite is a silicate mineral known for its variety of colors and often complex, multi-faceted crystal growth. It is highly prized by collectors for its strong fluorescence under ultraviolet light and its ability to be polished for lapidary work.
Spotting datolite in the field
Field marks- 1
Dense porcelain-like nodules, white or tinted, with a fine sugary texture inside
- 2
Michigan nodules often carry copper inclusions that give pink, red or orange coloring
- 3
Hardness 5 to 5.5, with a glassy to dull luster
Datolite is a specialty of the Keweenaw copper district in Michigan, where it formed as nodules in the basalt and often trapped native copper inside, producing pink, salmon and red coloring that collectors chase by locality. From the outside a datolite nodule is a plain white or grey lump in dark rock, so the material is found by working known mine dumps rather than by eye. Elsewhere it forms glassy crystals in traprock cavities.
Straight answers
- Is it worth cutting?
- Michigan copper-included datolite cabs beautifully and is highly collected by mine locality. Cut a window first, since the exterior tells you nothing about the color inside.
- What is it really worth?
- Moderate to high for Michigan copper datolite with strong color, and locality provenance genuinely affects price there.
- Can you legally keep it?
- Keweenaw mine dumps are private property. Fee-dig operations at several historic mines are the legal route.
Where it is worth going
- Keweenaw copper districtHoughton and Keweenaw counties, Michigan
Copper-included datolite nodules from historic mine dumps. Access through commercial fee digs.
Often confused with
Datolite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside datolite
Minerals reported to co-occur with datolite. 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
- Prismatic Crystals, Massive, Botryoidal, Granular
- Cleavage
- None
- Fluorescence
- Often Bright Yellow-green Under SW UV
- Rarity
- Common
- Uses
- Collector, Lapidary
- Host rock
- Hydrothermal Veins, Contact Metamorphic Rocks, Basalt Cavities
- Typical price
- $10-100 per specimen
Where rockhounds find datolite
21 mapped spotsClassic worldwide localities
- Lake Superior region, USA
- Dalnegorsk, Russia
- Charcas, Mexico
- Arendal, Norway
- Trentino, Italy
U.S. states with datolite
Each link opens a state-specific list of mapped rockhounding spots that produce datolite.
Field-hunting tip
Look in hydrothermal veins, contact metamorphic rocks, basalt cavities country, the host setting where datolite typically forms. If you start seeing calcite, prehnite, danburite in float, you are in the right ground. Field specimens usually show a prismatic crystals, massive, botryoidal, granular habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in New Jersey, Massachusetts, Michigan. Start trip planning there.
Common questions
How do you identify datolite?+
Where is datolite found?+
Can I find datolite in the United States?+
How much is datolite worth?+
What rocks look like datolite?+
What minerals are found with datolite?+
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What is datolite used for?+
Find datolite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
