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 6-6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous, pearly on cleavage.
- 4Match the color rangeCompare against the expected color range: white, gray, yellow, red, green, blue-green, bluish green, gray, grayish yellow, yellowish.
- 5Look at form & habitCrystal system: triclinic. Typical habit: blocky, crystalline, prismatic.
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
- 6-6.5
- Density
- 2.54-2.57 g/cm³
- Streak
- White
- Luster
- Vitreous, pearly on cleavage
- Transparency
- Transparent to translucent
- Crystal system
- Triclinic
- Crystal habit
- Blocky, crystalline, prismatic
- Cleavage
- Perfect on {001} and {010}, intersecting at ~90°; partings on {100}, {110}, {110}, and {201}
- Fluorescence
- Cherry red under SW UV
- Rarity
- Common
- Uses
- Collector, Decorative, Lapidary
- Host rock
- Common in plutonic felsic rocks, as granites, granite pegmatites, syenites; in metamorphic rocks of the greenschist and amphibolite facies; in hydrothermal veins
Where rockhounds find microcline
15 mapped spotsClassic worldwide localities
- Amelia, Amelia Co., Virginia, USA
- Haddam, Middlesex Co., Connecticut, USA
- Magnet Cove, Hot Spring Co., Arkansas, USA
- Pikes Peak area, El Paso Co., Crystal Peak, Teller Co., Devil's Hole beryl mine, Fremont Co., Colorado, USA
- Fredriksvärn, Arendal, and Larvik, Norway
- Ilmen Mountains, Ural Mountains, and on the Kola Peninsula, Russia
Field-hunting tip
Where it forms: Common in plutonic felsic rocks, as granites, granite pegmatites, syenites; in metamorphic rocks of the greenschist and amphibolite facies; in hydrothermal veins. If you start seeing quartz, sodic plagioclase, muscovite in float, you are in the right ground. Typical habit: blocky, crystalline, prismatic. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Connecticut, Utah, Alabama. Start trip planning there.
More microcline photos
Common questions
How do you identify microcline?+
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Find microcline on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
