An echinoid geode is a fossilized sea urchin that has had its internal cavity filled with secondary mineral crystals, typically quartz or calcite. Collectors look for well-defined external test (shell) features paired with a hollow interior lined with sparkling druzy crystals. They are most commonly recovered from limestone or marine sedimentary deposits where groundwater infiltration facilitated mineralization.
Is this echinoid geode?
3-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 echinoid geode with a known reference. Echinoid Geode sits at Mohs 7, softer than the next harder reference, harder than the previous one.
- 2Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 3Match the color rangeCompare against the expected color range: gray, white, clear, brown, tan.
Often confused with
Echinoid Geode vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside echinoid geode
Minerals reported to co-occur with echinoid geode. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 7
- Density
- 2.65 g/cm³
- Luster
- Vitreous
- Transparency
- Translucent
- Rarity
- Uncommon
- Uses
- Collector, Decorative
- Host rock
- sedimentary limestone
Where rockhounds find echinoid geode
1 mapped spotsClassic worldwide localities
- Florida
- Morocco
- Madagascar
- United Kingdom
Field-hunting tip
Where it forms: sedimentary limestone. If you start seeing quartz, calcite, chalcedony in float, you are in the right ground. In the U.S., the densest reported localities are in Florida. Start trip planning there.
Common questions
How do you identify echinoid geode?+
Where is echinoid geode found?+
Can I find echinoid geode in the United States?+
What rocks look like echinoid geode?+
What minerals are found with echinoid geode?+
What kind of rock does echinoid geode form in?+
What is echinoid geode used for?+
Find echinoid geode on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
