How to identify Orange Calcite

To correctly identify Orange Calcite (Calcite), 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

   Varies from pale orange to deep, saturated orange, sometimes with yellowish or reddish tints. The color is generally uniform but can show banding.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Vitreous (glassy) to resinous, sometimes dull on weathered surfaces.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Typically smooth to slightly granular, often exhibiting a waxy feel when polished.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Most commonly found as massive, granular, or stalactitic aggregates. Individual crystals, when present, are typically rhombohedral, scalenohedral, or prismatic. Twinning is common.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   Perfect rhombohedral cleavage in three directions, producing characteristic rhomb-shaped fragments when broken.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in a wide range of geological settings including sedimentary rocks (limestone, marble), hydrothermal veins, caves (as stalactites and stalagmites), and as a secondary mineral in igneous and metamorphic rocks. It often occurs in association with other carbonate minerals.

Key Facts

Hardness

3 (Mohs scale)

Specific Gravity

2.71 g/cm³

Crystal System

Trigonal

Color

Orange, yellowish-orange, reddish-orange

Luster

Vitreous to resinous

Transparency

Transparent to translucent

Fracture

Conchoidal to uneven

Cleavage

Perfect rhombohedral in three directions at 74°55'

Composition

Calcium Carbonate (CaCO3)

Physical characteristics

• Crystal Habit: Massive, granular, stalactitic, botryoidal, rhombohedral, scalenohedral, prismatic
• Cleavage Type: Perfect rhombohedral {1011}
• Fracture Type: Conchoidal to uneven
• Tenacity: Brittle
• Luster Type: Vitreous to resinous

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