Microcline is a common potassium-rich feldspar that forms essential components of many igneous rocks. It is most famously recognized by its vibrant green-to-blue variety, Amazonite, which is prized by collectors and lapidaries alike for its distinct color and luster.
Is this microcline?
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 microcline with a known reference. Microcline sits at Mohs 6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Microcline leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Microcline typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, gray, yellow, red, green, blue-green.
- 5Look at form & habitCrystal system: triclinic. Typical habit: prismatic crystals, often showing polysynthetic twinning.
Often confused with
Microcline vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside microcline
Minerals reported to co-occur with microcline. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KAlSi₃O₈
- Mohs hardness
- 6
- Density
- 2.5-2.6 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Prismatic Crystals, Often Showing Polysynthetic Twinning
- Cleavage
- Perfect in Two Directions At Nearly 90 Degrees
- Rarity
- Common
- Uses
- Collector, Decorative, Lapidary
- Host rock
- Granite Pegmatites
- Typical price
- $5-50 for small specimens, $100-500+ for high-quality Amazonite crystals
Where rockhounds find microcline
13 mapped spotsClassic worldwide localities
- Pikes Peak (Colorado, USA)
- Minas Gerais (Brazil)
- Norway
- Russia
- Madagascar
Field-hunting tip
Look in granite pegmatites country, the host setting where microcline typically forms. If you start seeing quartz, muscovite, biotite in float, you are in the right ground. Field specimens usually show a prismatic crystals, often showing polysynthetic twinning habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Utah, Alabama, Arizona. Start trip planning there.
Common questions
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Find microcline on the map
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