Keweenaw agates are iconic banded chalcedony nodules found within ancient basaltic lava flows of the Lake Superior region. They are highly prized by collectors for their intense red and orange banding caused by iron oxidation and their characteristic concentric fortification patterns.
Is this keweenaw agate?
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 keweenaw agate with a known reference. Keweenaw Agate sits at Mohs 6.5-7 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Keweenaw Agate leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Keweenaw Agate typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: red, orange, white, yellow, brown.
- 5Look at form & habitCrystal system: trigonal. Typical habit: banded nodules.
Often confused with
Keweenaw Agate vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Keweenaw Agate and waxy on Jasper.
How to tell apart: Luster reads vitreous on Keweenaw Agate and waxy on Flint Nodules.
How to tell apart: Luster reads vitreous on Keweenaw Agate and waxy on Chalcedony.
Often found alongside keweenaw agate
Minerals reported to co-occur with keweenaw agate. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SiO₂
- Mohs hardness
- 6.5-7
- Density
- 2.6-2.7 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Banded Nodules
- Cleavage
- None
- Rarity
- Common
- Uses
- Lapidary, Collector, Decorative
- Host rock
- Basaltic Lava Flows
- Typical price
- $5-50 for small nodules, higher for large polished specimens
Where rockhounds find keweenaw agate
4 mapped spotsClassic worldwide localities
- Keweenaw Peninsula, Michigan
- Lake Superior shores, Minnesota
- Ontario, Canada
- Wisconsin
Field-hunting tip
Look in basaltic lava flows country — that is the host setting where keweenaw agate typically forms. If you start seeing copper, datolite, prehnite in float, you are in the right ground. Field specimens usually show a banded nodules habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Michigan — start trip planning there.
More keweenaw agate photos
Common questions
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Find keweenaw agate on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
