How to identify Boxwork Jasper

To correctly identify Boxwork Jasper (Jasper (silica with iron oxides)), 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

   Predominantly red, brown, yellow, orange, often with contrasting lighter or darker veins and infillings. The colors are due to iron oxides.

2. 2

   Luster

   How the surface reflects light: metallic, vitreous, dull

   Dull to sub-vitreous (waxy) on fractured surfaces.

3. 3

   Texture

   Grain size and surface feel: coarse, fine, glassy

   Microgranular, dense, and compact. The defining characteristic is the 'boxwork' or cellular pattern, which is a macroscopic textural feature.

4. 4

   Crystal Form

   Shape of visible crystals or crystal faces

   Massive, microcrystalline aggregates. Individual crystals are not visible to the naked eye.

5. 5

   Cleavage

   How it breaks: flat cleavage planes vs irregular fracture

   None, due to its microcrystalline nature.

6. 6

   Geological Environment

   The rock formation and setting where it occurs

   Hydrothermal alteration zones, weathered zones of sulfide deposits, or areas where carbonate or evaporite rocks have been dissolved and subsequently silicified. Often found in association with iron-rich host rocks or mineralized veins.

Key Facts

Hardness

6.5-7 on the Mohs scale

Specific Gravity

2.58-2.91 (typically around 2.65-2.66 for pure quartz, higher with iron oxides)

Crystal System

Trigonal (for microcrystalline quartz/chalcedony component)

Color

Red, brown, yellow, orange, often multi-colored with distinct patterns

Luster

Dull to waxy (sub-vitreous)

Transparency

Opaque

Fracture

Conchoidal to splintery

Cleavage

None

Composition

Silicon dioxide (SiO2) with significant inclusions of iron oxides (Fe2O3, FeO(OH)) and other mineral impurities.

Physical characteristics

• Crystal Habit: Massive, microcrystalline aggregates forming cellular or reticulated patterns.
• Cleavage Type: Absent
• Fracture Type: Conchoidal to splintery, uneven
• Tenacity: Brittle
• Luster Type: Dull to waxy

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