Horse Mountain Agate is a highly sought-after variety of microcrystalline quartz known for its vibrant red to orange banding and occasional plume-like inclusions. It typically forms within the vesicles of volcanic rhyolite and is prized by lapidary artists for its ability to take a high polish. Collectors should look for specimens with distinct fortification patterns and high translucency.
Is this horse mountain 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 horse mountain agate with a known reference. Horse Mountain 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. Horse Mountain Agate leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Horse Mountain Agate typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: red, orange, yellow, white, clear.
- 5Look at form & habitCrystal system: trigonal. Typical habit: botryoidal.
Often confused with
Horse Mountain Agate vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Horse Mountain Agate and vitreous to waxy on Carnelian.
How to tell apart: Luster reads vitreous on Horse Mountain Agate and waxy on Jasper.
How to tell apart: Luster reads vitreous on Horse Mountain Agate and waxy on Fire Agate.
Often found alongside horse mountain agate
Minerals reported to co-occur with horse mountain 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
- 2.65 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Botryoidal
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Lapidary, Collector, Decorative
- Host rock
- Volcanic Rhyolite
- Typical price
- $10-100 per specimen
Where rockhounds find horse mountain agate
1 mapped spotsClassic worldwide localities
- Horse Mountain, Humboldt County, Nevada, USA
Field-hunting tip
Look in volcanic rhyolite country, the host setting where horse mountain agate typically forms. If you start seeing quartz, opal, chalcedony in float, you are in the right ground. Field specimens usually show a botryoidal habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Tennessee. Start trip planning there.
Common questions
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Find horse mountain agate on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
