How to identify Peridot

To correctly identify Peridot (Olivine (gemstone variety)), 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

   Ranges from yellowish-green to pure green to brownish-green. The most desirable color is a vivid, intense green.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous (glassy) to oily.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Smooth to the touch when polished; rough in its natural crystal form.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Orthorhombic system, typically forming stubby prismatic crystals, often with striations. Can also be found as granular aggregates.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Poor to indistinct in two directions (parallel to {010} and {110}). Fracture is conchoidal.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in mafic and ultramafic igneous rocks (e.g., basalts, peridotites, dunites), especially as xenoliths in volcanic rocks. Also occurs in some metamorphic rocks and pallasite meteorites.

Key Facts

Hardness

6.5-7 on Mohs scale

Specific Gravity

3.27-3.48

Crystal System

Orthorhombic

Color

Green (yellowish-green, pure green, brownish-green)

Luster

Vitreous to oily

Transparency

Transparent to translucent

Fracture

Conchoidal

Cleavage

Poor to indistinct in two directions ({010} and {110})

Composition

Magnesium iron silicate, (Mg,Fe)2SiO4

Physical characteristics

• Crystal Habit: Prismatic, tabular, granular, massive
• Cleavage Type: Poor to indistinct, {010} and {110}
• Fracture Type: Conchoidal
• Tenacity: Brittle
• Luster Type: Vitreous to oily

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