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How to identify Carnelian and Citrine Quartz

SiO2 (Carnelian is a variety of Chalcedony, Citrine is a variety of Quartz)

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To correctly identify Carnelian and Citrine Quartz (SiO2 (Carnelian is a variety of Chalcedony, Citrine is a variety of 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

    Carnelian: Translucent to opaque, reddish-orange to reddish-brown. Citrine: Transparent to translucent, yellow, golden, or orange-brown.

  2. 2

    Luster

    How the surface reflects light: metallic, vitreous, dull

    Vitreous (glassy) to waxy for Carnelian; Vitreous (glassy) for Citrine.

  3. 3

    Texture

    Grain size and surface feel: coarse, fine, glassy

    Carnelian: Smooth, often conchoidal fracture surfaces. Citrine: Smooth, conchoidal fracture surfaces.

  4. 4

    Crystal Form

    Shape of visible crystals or crystal faces

    Carnelian: Typically massive, botryoidal, or stalactitic aggregates; individual crystals are microscopic. Citrine: Prismatic hexagonal crystals, often terminated, or massive.

  5. 5

    Cleavage

    How it breaks: flat cleavage planes vs irregular fracture

    None (both are varieties of quartz).

  6. 6

    Geological Environment

    The rock formation and setting where it occurs

    Carnelian: Found in amygdules, veins, and as nodular masses in volcanic rocks (e.g., basalts, andesites) and sedimentary deposits (e.g., gravels, conglomerates). Citrine: Occurs in hydrothermal veins, pegmatites, and igneous and metamorphic rocks. Often found in geodes and alluvial deposits.

Key Facts

Hardness
7 (Mohs scale)
Specific Gravity
2.58 - 2.64 (Carnelian); 2.65 (Citrine)
Crystal System
Trigonal
Color
Carnelian: Reddish-orange to reddish-brown. Citrine: Yellow, golden, orange-brown.
Luster
Vitreous to waxy (Carnelian); Vitreous (Citrine).
Transparency
Translucent to opaque (Carnelian); Transparent to translucent (Citrine).
Fracture
Conchoidal
Cleavage
None
Composition
Silicon Dioxide (SiO2)

Physical characteristics

  • Crystal Habit: Carnelian: Cryptocrystalline, massive, botryoidal, nodular. Citrine: Prismatic hexagonal crystals, often terminated, massive.
  • Cleavage Type: None
  • Fracture Type: Conchoidal
  • Tenacity: Brittle
  • Luster Type: Vitreous to waxy (Carnelian); Vitreous (Citrine)

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