How to identify Red Jasper

To correctly identify Red Jasper (Silicon Dioxide (SiO2)), 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

   Typically brick red, deep red, reddish-brown, or scarlet. The color is generally uniform or can exhibit subtle banding or patterns.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Dull to vitreous, often waxy when polished.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Smooth, dense, and fine-grained. Fracture surfaces are typically conchoidal and can feel sharp.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Cryptocrystalline, meaning no visible crystals to the naked eye. Forms in massive, nodular, or vein-filling habits.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None. Exhibits conchoidal fracture.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Found in association with volcanic rocks, hydrothermal veins, and as a component of sedimentary chert beds. It can also occur as infillings in fissures and cavities in various rock types.

Key Facts

Hardness

6.5-7 on the Mohs scale

Specific Gravity

2.58-2.91

Crystal System

Trigonal (as quartz), but cryptocrystalline

Color

Red, reddish-brown, scarlet

Luster

Dull, waxy, vitreous

Transparency

Opaque

Fracture

Conchoidal

Cleavage

None

Composition

Silicon Dioxide (SiO2) with iron oxide (hematite) inclusions

Physical characteristics

• Crystal Habit: Massive, nodular, botryoidal, or as vein fillings. Cryptocrystalline aggregates.
• Cleavage Type: Absent
• Fracture Type: Conchoidal to splintery
• Tenacity: Brittle
• Luster Type: Dull to waxy, sometimes sub-vitreous

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