How to identify Unakite

To correctly identify Unakite (Granite (Epidote, Pink Feldspar, Quartz)), 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

   Mottled green (epidote), pink (feldspar), and colorless/grey (quartz). The green can range from yellowish-green to dark pistachio-green, and the pink from salmon to reddish-pink.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous to sub-vitreous for quartz and feldspar, resinous to vitreous for epidote.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Granitic, medium to coarse-grained, interlocking crystalline texture.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Anhedral to subhedral grains of quartz, feldspar, and epidote, typically massive.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Feldspar exhibits two distinct cleavages at or near 90 degrees. Epidote has one perfect cleavage. Quartz has no cleavage.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Formed in areas where granitic rocks have undergone hydrothermal alteration, often associated with regional metamorphism or contact metamorphism near intrusive bodies, particularly along fault zones or shear zones where fluid flow is concentrated.

Key Facts

Hardness

6-7 on Mohs scale (due to quartz and feldspar, epidote is 6-7).

Specific Gravity

2.85 - 3.20 (varies with mineral proportions, epidote is denser).

Crystal System

Monoclinic (epidote, K-feldspar), Trigonal (quartz). Unakite itself is a rock, not a single mineral, so it doesn't have a single crystal system.

Color

Pistachio-green, pink, and colorless/grey.

Luster

Vitreous to sub-vitreous.

Transparency

Opaque to translucent.

Fracture

Conchoidal (quartz), uneven to splintery (feldspar, epidote).

Cleavage

Good in feldspar (2 directions), perfect in epidote (1 direction), none in quartz.

Composition

Primarily composed of epidote (Ca2(Al,Fe)3(SiO4)3(OH)), potassium feldspar (KAlSi3O8, typically orthoclase), and quartz (SiO2).

Physical characteristics

• Crystal Habit: Massive, granular aggregates of interlocking crystals.
• Cleavage Type: Feldspar: two distinct cleavages at ~90 degrees. Epidote: one perfect basal cleavage {001}. Quartz: no cleavage.
• Fracture Type: Conchoidal (quartz), uneven to splintery (feldspar, epidote).
• Tenacity: Brittle.
• Luster Type: Vitreous to sub-vitreous.

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