Banded Rhyolite (likely Green Jasper/Agate variety)

Physical Properties

Hardness: 6.5-7. Color: Green, tan, and light teal bands. Luster: Vitreous to waxy (especially when polished). Crystal structure: Trigonal/Microcrystalline. Cleavage: None (conchoidal fracture).

Formation & Geological History

Formed from silica-rich volcanic fluid or ash that cools rapidly, often with secondary mineralization filling cavities or layers during hydrothermal activity. These specimens often date to the Tertiary or Cretaceous periods depending on location.

Uses & Applications

Primarily used for lapidary work, jewelry making (cabochons), interior decoration, and as a popular specimen for rock collectors and metaphysical enthusiasts.

Geological Facts

The distinct layering is known as flow-banding, caused by friction as the thick, viscous lava moved. Similar green-banded stones from specific regions are often marketed as 'Rainforest Jasper' or 'Green Zebra Jasper'.

Field Identification & Locations

Identify by its parallel, often wavy mineral bands and its high hardness (it cannot be scratched by a steel knife). Commonly found in volcanic regions of Oregon (USA), Madagascar, and Australia.

Identified on: 4/13/2026

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