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
12 mapped spotsClassic worldwide localities
- Pikes Peak (Colorado, USA)
- Minas Gerais (Brazil)
- Norway
- Russia
- Madagascar
Field-hunting tip
Look in granite pegmatites country — that is 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 Maine, Utah, Alabama — start trip planning there.
Common questions
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Find microcline on the map
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