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, 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.
