How to identify Red Jasper

To correctly identify Red Jasper (SiO2 (cryptocrystalline 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

   Typically brick red, deep red, reddish-brown, or scarlet. Can sometimes have darker or lighter streaks or patterns.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Dull to vitreous (glassy) on fractured surfaces, often waxy to dull when unpolished.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Smooth, dense, and fine-grained. Opaque.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Massive, nodular, or as fillings in veins and fissures. Does not form macroscopic crystals.

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 sedimentary deposits (e.g., chert beds), hydrothermal veins, and as secondary infillings in volcanic and metamorphic rocks. Often associated with iron-rich sediments.

Key Facts

Hardness

6.5-7 on Mohs scale

Specific Gravity

2.58-2.91

Crystal System

Trigonal (microcrystalline aggregates)

Color

Red, reddish-brown, scarlet

Luster

Dull to vitreous, waxy

Transparency

Opaque

Fracture

Conchoidal to splintery

Cleavage

None

Composition

Silicon dioxide (SiO2) with iron oxide (hematite) impurities

Physical characteristics

• Crystal Habit: Massive, nodular, botryoidal, or as vein fillings. Microcrystalline aggregates.
• Cleavage Type: None
• Fracture Type: Conchoidal to splintery, uneven
• Tenacity: Brittle
• Luster Type: Dull to waxy, vitreous on fresh fracture

Explore Red Jasper