Purple agate is a cryptocrystalline variety of quartz characterized by its fine-grained structure and distinct banded or variegated purple coloration. It typically forms within cavities of volcanic rocks as concentric layers deposited from silica-rich fluids.
Is this purple 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 purple agate with a known reference. Purple 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. Purple Agate leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Purple Agate typically shows a waxy luster.
- 4Match the color rangeCompare against the expected color range: purple, violet, lavender.
- 5Look at form & habitCrystal system: trigonal. Typical habit: massive.
Often confused with
Purple Agate vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads waxy on Purple Agate and vitreous on Amethyst.
How to tell apart: Purple Agate is noticeably harder (Mohs 6.5-7 vs. 4); luster reads waxy on Purple Agate and vitreous on Fluorite.
Often found alongside purple agate
Minerals reported to co-occur with purple 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
- 2.60-2.65 g/cm³
- Streak
- White
- Luster
- Waxy
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Common
- Uses
- Lapidary, Ornamental, Collector
- Host rock
- Volcanic Cavities
- Typical price
- $5-50 for small slabs or cabochons
Where rockhounds find purple agate
3 mapped spotsClassic worldwide localities
- Brazil
- Mexico
- USA
- Uruguay
Field-hunting tip
Look in volcanic cavities country — that is the host setting where purple agate typically forms. If you start seeing quartz, calcite, zeolites 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 Arizona, Nevada, Oregon — start trip planning there.
Common questions
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Find purple agate on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
