How to identify Unakite

To correctly identify Unakite (Unakite (Epidote, Orthoclase, 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/reddish-orange (orthoclase), and colorless/grey (quartz).

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous to sub-vitreous for quartz and epidote, pearly to vitreous for orthoclase.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Granitic to granular, often with interlocking crystals. Can be fine-grained to coarse-grained.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Individual mineral components (epidote, orthoclase, quartz) exhibit their characteristic crystal forms within the rock matrix. Epidote often appears as granular aggregates or prismatic crystals, orthoclase as anhedral to subhedral grains, and quartz as anhedral grains filling interstitial spaces.

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.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Formed in areas of regional metamorphism or hydrothermal alteration, typically associated with granitic batholiths or intrusive bodies.

Key Facts

Hardness

6-7 on the Mohs scale (due to its constituent minerals: Quartz 7, Epidote 6-7, Orthoclase 6).

Specific Gravity

2.85 - 3.20 (variable depending on mineral proportions, epidote is denser).

Crystal System

Monoclinic (Epidote, Orthoclase), Trigonal (Quartz). Unakite itself is a rock, not a single crystal.

Color

Mottled green, pink/red, and colorless/grey.

Luster

Vitreous to sub-vitreous.

Transparency

Opaque to translucent.

Fracture

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

Cleavage

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

Composition

A rock composed primarily of Epidote (Ca2(Al,Fe)3(SiO4)3(OH)), Orthoclase (KAlSi3O8), and Quartz (SiO2).

Physical characteristics

• Crystal Habit: Granular to massive, with individual mineral grains exhibiting their characteristic habits within the rock.
• Cleavage Type: Orthoclase: perfect in two directions at 90 degrees. Epidote: good in one direction. Quartz: none.
• Fracture Type: Conchoidal (quartz), uneven to splintery (epidote, orthoclase).
• Tenacity: Brittle.
• Luster Type: Vitreous to sub-vitreous.

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