Agatized Coral
A variety of Coral
What is Agatized Coral?
Fossilized corals are often collectively called agatized Coral although some are actually calcite textured. The cross-section pattern of the fossilized corals when polished is attractive to the collecters. Agatized Coral is the state symbol of Michigan (know as "petoskey stone") and Florida in the USA.
Optical Properties
- Refractive Index
- 1.486-1.658
- Birefringence
- 0.160-0.172
- Pleochroism
- None
- Optical Character
- Uniaxial negative
Discover Values
This stone excels in beauty, cultural value, collection value.
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Agatized Coral before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Agatized Coral Localities Map
See where Agatized Coral is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Health & Safety Information
- ⚠️Agatized Coral in powdered form can be toxic due to its Crystalline Silica content.
- ⚠️Agatized Coral is typically non-toxic unless it's in powder form. Long-term exposure to finely ground powder may lead to silicosis. Therefore, when cutting or polishing agatized Coral, be sure to wear a dust mask to avoid inhaling its dust.
Quick Facts
Physical Properties
- Color
- White to cream, red, gray, orange, yellow, brown, black, blue, etc.
- Hardness (Mohs)
- 6.5 - 7
- Density
- 2.6 - 2.7 g/cm³
- Streak
- White
Chemical Properties
- Chemical Formula
- SiO2
- Elements
- Si, O
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Agatized Coral FAQs
How do I identify Agatized Coral?
Agatized Coral can be identified by its hardness of 6.5 - 7 on the Mohs scale, White to cream color. Look for these key characteristics when examining specimens.
What color is Agatized Coral?
Agatized Coral typically appears in White to cream, red, gray, orange, yellow, brown, black, blue, etc.. Color can vary depending on impurities and formation conditions.
How hard is Agatized Coral?
Agatized Coral has a hardness of 6.5 - 7 on the Mohs scale. This gives it moderate hardness.
