Dendritic Agate is a variety of chalcedony characterized by tree-like or fern-like inclusions known as dendrites. These delicate, dark-colored patterns are caused by the presence of manganese or iron oxides, which grow within fractures or spaces in the silica. It is highly sought after by lapidary artists for cutting into unique, picture-like cabochons.
Is this dendritic 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 dendritic agate with a known reference. Dendritic 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. Dendritic Agate leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Dendritic Agate typically shows a waxy luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, gray, brown, black.
- 5Look at form & habitCrystal system: trigonal. Typical habit: massive.
Often confused with
Dendritic Agate vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside dendritic agate
Minerals reported to co-occur with dendritic 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
- Waxy
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Common
- Uses
- Lapidary, Collector, Decorative
- Host rock
- Volcanic Rocks
- Typical price
- $5-50 for slabs and cabochons
Where rockhounds find dendritic agate
1 mapped spotsClassic worldwide localities
- Brazil
- India
- USA
- Mexico
- Madagascar
Field-hunting tip
Look in volcanic rocks country — that is the host setting where dendritic agate typically forms. If you start seeing quartz, chalcedony, calcite in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in California — start trip planning there.
Common questions
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Find dendritic agate on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
