How to identify Amazonite

To correctly identify Amazonite (Amazonite (variety of Microcline Feldspar)), check each of these features in order. Many rocks and minerals look alike, so cross-reference multiple properties before deciding.

Step-by-step identification

1. 1

   Color

   Overall color and any zoning or banding

   Characteristic blue-green to green, sometimes with white streaks or inclusions. The color can vary in intensity.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous (glassy) to pearly on cleavage surfaces.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Typically massive or in well-formed, often tabular, crystals. Can exhibit a fine lamellar twinning (perthitic texture) visible on polished surfaces.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Usually forms in anhedral to subhedral masses, but can also occur as distinct, often blocky or tabular, triclinic crystals. Twinning, particularly polysynthetic twinning (albite twinning) and pericline twinning, is common and can be observed as fine striations on cleavage surfaces.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Perfect cleavage in two directions, nearly at right angles (approximately 90 degrees, specifically 90° 30'). This is characteristic of feldspar minerals.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Primarily found in granitic pegmatites, which are igneous intrusions characterized by very large crystals. Less commonly found in granites and some metamorphic rocks.

Key Facts

Hardness

6 to 6.5 on the Mohs scale

Specific Gravity

2.56 to 2.58

Crystal System

Triclinic

Color

Blue-green, green, sometimes with white streaks

Luster

Vitreous to pearly

Transparency

Translucent to opaque

Fracture

Uneven to conchoidal

Cleavage

Perfect in two directions, nearly at 90 degrees (90° 30')

Composition

Potassium aluminum silicate (KAlSi3O8)

Physical characteristics

• Crystal Habit: Massive, granular, or in well-formed tabular to blocky crystals, often twinned.
• Cleavage Type: Perfect basal {001} and good prismatic {010}, intersecting at approximately 90° 30'.
• Fracture Type: Uneven to conchoidal.
• Tenacity: Brittle.
• Luster Type: Vitreous on crystal faces, pearly on cleavage surfaces.

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