How to identify Red Jasper

To correctly identify Red Jasper (Jasper (variety of Chalcedony, microcrystalline 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. The color is uniform or can exhibit banding, orbicular patterns, or brecciated textures.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

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

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

   Microcrystalline aggregates; individual crystals are not visible to the naked eye. Forms massive, nodular, or botryoidal 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 sedimentary deposits (e.g., banded iron formations, chert beds), hydrothermal veins, volcanic rocks (as infillings or replacements), and as secondary mineralization in various host rocks. Often associated with areas of past volcanic activity or silica-rich fluid circulation.

Key Facts

Hardness

6.5-7 on Mohs scale

Specific Gravity

2.58-2.64 g/cm³

Crystal System

Trigonal (microcrystalline aggregates)

Color

Red, brick red, reddish-brown, scarlet

Luster

Dull, vitreous, waxy

Transparency

Opaque

Fracture

Conchoidal to splintery

Cleavage

None

Composition

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

Physical characteristics

• Crystal Habit: Massive, nodular, botryoidal, stalactitic, or as vein fillings. Microcrystalline, so no visible individual crystals.
• Cleavage Type: None
• Fracture Type: Conchoidal to splintery, uneven
• Tenacity: Brittle
• Luster Type: Dull to vitreous, waxy

Explore Red Jasper