Chalcedony is a cryptocrystalline form of silica that typically forms in rounded, waxy masses or botryoidal crusts within volcanic vugs. Rockhounders often look for its distinctive waxy luster and conchoidal fracture, making it a favorite material for cabochons and lapidary work.

Hardness

6.5-7

Mohs

Luster

Waxy

Streak

White

Transparency

Translucent

mineralcommonQuartz family

Chalcedony

Also: white agate

Hardness: 6.5-7
Luster: Waxy
Streak: White
Transparency: Translucent

Is this chalcedony?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch chalcedony with a known reference. Chalcedony sits at Mohs 6.5-7 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Chalcedony leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Chalcedony typically shows a waxy luster.
4
Match the color range
Compare against the expected color range: white, gray, blue, brown, tan.
5
Look at form & habit
Crystal system: trigonal. Typical habit: botryoidal, massive, crusts, stalactitic.

Often confused with

Chalcedony vs. its common look-alikes — and how to tell them apart in the field.

mineral

Opalite

Mohs 5.5-6.5

How to tell apart: Luster reads waxy on Chalcedony and vitreous on Opalite.

Often found alongside chalcedony

Minerals reported to co-occur with chalcedony. 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: 2.58-2.64 g/cm³
Colors: White Gray Blue Brown Tan
Streak: White
Luster: Waxy
Transparency: Translucent
Crystal system: Trigonal
Crystal habit: Botryoidal, Massive, Crusts, Stalactitic
Cleavage: None
Rarity: Common
Uses: Lapidary, Decorative, Collector
Host rock: Volcanic Cavities, Hydrothermal Veins, Sedimentary Nodules
Typical price: $5-50 for small specimens, higher for unique collector pieces

Where rockhounds find chalcedony

262 mapped spots

Classic worldwide localities

Brazil
India
Madagascar
USA
Mexico

U.S. states with chalcedony

Each link opens a state-specific list of mapped rockhounding spots that produce chalcedony.

Field-hunting tip

Look in volcanic cavities, hydrothermal veins, sedimentary nodules country — that is the host setting where chalcedony typically forms. If you start seeing quartz, calcite, zeolites in float, you are in the right ground. Field specimens usually show a botryoidal, massive, crusts, stalactitic habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Utah, Oregon, Wyoming — start trip planning there.

Browse 262 U.S. spots for chalcedony →

Common questions

How do you identify chalcedony?+

Mohs hardness is 6.5-7. It typically shows a waxy luster. The streak is white. Common colors include white, gray, blue, brown.

Where is chalcedony found?+

Notable localities include Brazil; India; Madagascar; USA; Mexico.

Can I find chalcedony in the United States?+

RockHoundR maps 262 chalcedony rockhounding spots across 12 U.S. states — the top states are Utah, Oregon, Wyoming.

How much is chalcedony worth?+

Typical asking prices fall in the range of $5-50 for small specimens, higher for unique collector pieces. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like chalcedony?+

Chalcedony is most often confused with Opalite, Flint Nodules, Jasper. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with chalcedony?+

Chalcedony commonly co-occurs with Quartz, Calcite, Zeolites, Goethite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does chalcedony form in?+

Chalcedony typically forms in volcanic cavities, hydrothermal veins, sedimentary nodules. Working float back to the host body is the standard way to chase a fresh occurrence.

What is chalcedony used for?+

Chalcedony is used in lapidary, decorative, collector.

Find chalcedony on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.