How to identify Tumbled Jasper

To correctly identify Tumbled Jasper (Jasper (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

   Extremely variable; commonly red, brown, yellow, green, or a combination of these. Often patterned, banded, or orbicular. Rarely blue.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Dull to vitreous (glassy) on fresh fracture, waxy to dull on unpolished surfaces. Tumbled Jasper will have a vitreous to waxy luster due to polishing.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Fine-grained, dense, and opaque. Tumbled Jasper will feel smooth and cool to the touch.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Massive, cryptocrystalline (microcrystalline), meaning individual crystals are too small to be seen without high 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 a variety of geological settings, including hydrothermal veins, volcanic rocks (as infillings or replacements), sedimentary deposits (as nodules or beds), and metamorphic rocks. Often associated with iron formations, chert beds, and areas of past volcanic activity.

Key Facts

Hardness

7 (Mohs scale)

Specific Gravity

2.58 - 2.91 g/cm³ (typically 2.65 - 2.66)

Crystal System

Trigonal (cryptocrystalline aggregates)

Color

Red, brown, yellow, green, gray, black, often multi-colored and patterned

Luster

Dull to waxy (rough), vitreous to waxy (tumbled/polished)

Transparency

Opaque

Fracture

Conchoidal to splintery

Cleavage

None

Composition

Silicon dioxide (SiO2) with various mineral inclusions

Physical characteristics

• Crystal Habit: Massive, cryptocrystalline aggregates; does not form macroscopic crystals.
• Cleavage Type: None
• Fracture Type: Conchoidal to splintery, due to its microcrystalline structure.
• Tenacity: Brittle
• Luster Type: Dull to waxy on unpolished surfaces; vitreous (glassy) on polished surfaces or fresh fractures.

Explore Tumbled Jasper