How to identify Red Jasper

To correctly identify Red Jasper (Microcrystalline Quartz (Chalcedony variety)), 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 opaque red, reddish-brown, or brick-red. Can sometimes have patterns or banding of different shades of red or other colors.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Dull to vitreous (glassy) on fractured surfaces, often waxy or greasy on polished surfaces.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Fine-grained, dense, and compact. Feels smooth to the touch.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Massive, cryptocrystalline (crystals too small to be seen without magnification). 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 association with volcanic rocks, hydrothermal alteration zones, sedimentary deposits (e.g., chert beds), and as a component of some banded iron formations.

Key Facts

Hardness

6.5 - 7 on the Mohs scale

Specific Gravity

2.58 - 2.91 g/cm³

Crystal System

Trigonal (cryptocrystalline aggregates)

Color

Red, reddish-brown, brick-red, often with patterns

Luster

Dull, waxy, or vitreous

Transparency

Opaque

Fracture

Conchoidal to splintery

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: None
• Fracture Type: Conchoidal to splintery, uneven
• Tenacity: Brittle
• Luster Type: Dull to waxy, sometimes vitreous on fresh fracture

Explore Red Jasper