Pearls are organic gemstones produced by living mollusks as a defense mechanism against irritants, composed primarily of calcium carbonate in the form of nacre. They are prized for their unique orient and luster, and can be found in both saltwater and freshwater environments. Collectors value them for their high degree of symmetry, color, and surface smoothness.
Is this pearls?
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 pearls with a known reference. Pearls sits at Mohs 2.5-4.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Pearls leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Pearls typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: white, cream, pink, gold, black, silver.
- 5Look at form & habitTypical habit: concretionary.
All properties
- Chemical formula
- CaCO₃
- Mohs hardness
- 2.5-4.5
- Density
- 2.6-2.8 g/cm³
- Streak
- White
- Luster
- Pearly
- Transparency
- Translucent
- Crystal habit
- Concretionary
- Cleavage
- None
- Fluorescence
- Often Inert, But Some May Show White or Blue Under UV
- Rarity
- Common
- Uses
- Gemstone, Jewelry
- Host rock
- Organic Biological Environments (mollusks)
- Typical price
- $10-10000+ depending on size, luster, and origin
Where rockhounds find pearls
5 mapped spotsClassic worldwide localities
- Persian Gulf
- French Polynesia
- Japan
- Australia
- Philippines
Field-hunting tip
Look in organic biological environments (mollusks) country — that is the host setting where pearls typically forms. Field specimens usually show a concretionary habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Wisconsin, Iowa, Tennessee — start trip planning there.
Common questions
How do you identify pearls?+
Where is pearls found?+
Can I find pearls in the United States?+
How much is pearls worth?+
What kind of rock does pearls form in?+
What is pearls used for?+
Find pearls on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
