How to identify Unakite

To correctly identify Unakite (Unakite), 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 pink (orthoclase), green (epidote), and often colorless/gray (quartz). The green can range from yellowish-green to dark olive 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 to granular, often with interlocking crystals visible to the naked eye. Can be medium to coarse-grained.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Individual mineral components (quartz, orthoclase, epidote) exhibit their characteristic crystal forms within the rock matrix, though often anhedral due to interlocking growth.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Orthoclase exhibits two distinct cleavages at nearly 90 degrees. Epidote has one perfect cleavage. Quartz has no cleavage but exhibits conchoidal fracture.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in areas where granitic rocks have undergone regional or contact metamorphism and hydrothermal alteration, particularly in orogenic belts and ancient continental shields.

Key Facts

Hardness

6-7 on Mohs scale (due to quartz and feldspar components)

Specific Gravity

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

Crystal System

Monoclinic (epidote, orthoclase), Trigonal (quartz)

Color

Mottled pink, green, and colorless/gray

Luster

Vitreous to sub-vitreous

Transparency

Opaque to translucent

Fracture

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

Cleavage

Good in orthoclase (two directions at ~90°), perfect in epidote (one direction), none in quartz

Composition

A granitoid rock composed primarily of epidote (Ca2(Al,Fe)3(SiO4)3(OH)), orthoclase feldspar (KAlSi3O8), and quartz (SiO2).

Physical characteristics

• Crystal Habit: Granular, massive, anhedral interlocking crystals.
• Cleavage Type: Good in orthoclase (prismatic), perfect in epidote (basal).
• Fracture Type: Conchoidal (quartz), uneven to splintery (feldspar, epidote).
• Tenacity: Brittle.
• Luster Type: Vitreous to sub-vitreous.

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