How to identify Serpentinite with Quartz Veins

To correctly identify Serpentinite with Quartz Veins (Serpentinite (metamorphic rock) with Quartz (SiO2) veins), 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

   Serpentinite matrix: Dark green, olive green, yellowish-green, blackish-green. Quartz veins: White, gray, colorless, translucent.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Serpentinite matrix: Greasy, waxy, silky (chrysotile), dull. Quartz veins: Vitreous (glassy).

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Serpentinite matrix: Massive, fine-grained, sometimes fibrous (chrysotile), often slickensided. Quartz veins: Crystalline, granular, sometimes banded.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Serpentine minerals are typically anhedral to subhedral, forming interlocking masses or fibrous aggregates. Quartz in veins forms anhedral to euhedral crystals, often prismatic, filling fractures.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Serpentine minerals: Perfect basal cleavage (chrysotile), good to perfect (antigorite, lizardite). Quartz: No true cleavage, conchoidal fracture.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Ophiolite complexes (obducted oceanic crust), subduction zones, fault zones within ultramafic bodies, metamorphic terranes where ultramafic rocks have been hydrated.

Key Facts

Hardness

Serpentine minerals: 2.5-4 (Mohs). Quartz: 7 (Mohs). The overall rock hardness will vary depending on the proportion and distribution of each component.

Specific Gravity

Serpentinite: 2.5-2.9. Quartz: 2.65.

Crystal System

Serpentine minerals: Monoclinic (antigorite, lizardite) or Orthorhombic (chrysotile). Quartz: Trigonal.

Color

Serpentinite: Green, yellowish-green, blackish-green. Quartz: Colorless, white, gray.

Luster

Serpentinite: Greasy, waxy, silky. Quartz: Vitreous.

Transparency

Serpentinite: Translucent to opaque. Quartz: Transparent to translucent.

Fracture

Serpentinite: Uneven, splintery, conchoidal (less common). Quartz: Conchoidal.

Cleavage

Serpentine minerals: Perfect basal (chrysotile), good to perfect (antigorite, lizardite). Quartz: None.

Composition

Serpentinite: Hydrous magnesium iron phyllosilicate ((Mg,Fe)3Si2O5(OH)4). Quartz: Silicon dioxide (SiO2).

Physical characteristics

• Crystal Habit: Serpentine: Massive, platy, fibrous (chrysotile). Quartz: Prismatic, massive, granular.
• Cleavage Type: Serpentine: Basal (perfect in chrysotile, good in others). Quartz: None.
• Fracture Type: Serpentine: Uneven, splintery. Quartz: Conchoidal.
• Tenacity: Serpentine: Tough, sometimes flexible (chrysotile). Quartz: Brittle.
• Luster Type: Serpentine: Greasy, waxy, silky. Quartz: Vitreous.

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