How to identify Chrysoprase

To correctly identify Chrysoprase (Chalcedony (cryptocrystalline quartz) with nickel inclusions), 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

   Apple-green to deep green, sometimes yellowish-green. The color is typically uniform but can show slight banding or mottling.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous to waxy, dull on unpolished surfaces.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Smooth, microgranular, conchoidal fracture surfaces.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Cryptocrystalline aggregates, typically massive, botryoidal, or stalactitic. Individual crystals are microscopic and not visible to the naked eye.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None, due to its cryptocrystalline nature.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in weathered zones of nickel-rich ultramafic rocks (e.g., serpentinites, dunites) and lateritic nickel deposits. Often associated with magnesite, opal, and other secondary minerals.

Key Facts

Hardness

6.5-7 on the Mohs scale

Specific Gravity

2.58-2.64

Crystal System

Trigonal (as quartz, but cryptocrystalline aggregates appear amorphous)

Color

Apple-green, yellowish-green, deep green

Luster

Vitreous to waxy

Transparency

Translucent to opaque

Fracture

Conchoidal to uneven

Cleavage

None

Composition

Silicon dioxide (SiO2) with trace nickel (Ni) impurities

Physical characteristics

• Crystal Habit: Massive, botryoidal, stalactitic, nodular aggregates. Individual crystals are microscopic.
• Cleavage Type: None
• Fracture Type: Conchoidal to uneven
• Tenacity: Brittle
• Luster Type: Vitreous to waxy

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