mineral
Green mineral specimen (likely prehnite or chrysoprase)
Tentatively prehnite, Ca₂Al₂Si₃O₁₀(OH)₂; chrysoprase (microcrystalline quartz) is an alternative
AI-generated identification · may be incorrectPale blue-green, translucent, with a vitreous to waxy luster and irregular granular surface. Identification is limited by the close-up image; hardness would be about 6–6.5 (prehnite) or 6.5–7 (chrysoprase), with no obvious cleavage visible.
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Physical properties
Pale blue-green, translucent, with a vitreous to waxy luster and irregular granular surface. Identification is limited by the close-up image; hardness would be about 6–6.5 (prehnite) or 6.5–7 (chrysoprase), with no obvious cleavage visible.
Formation & geological history
Prehnite forms in cavities of basalt and other volcanic rocks from low-temperature hydrothermal fluids; chrysoprase forms when nickel-bearing silica alters ultramafic rocks. Both are geologically young compared with Earth’s oldest rocks.
Uses & applications
Attractive pieces are used as lapidary material, cabochons, beads, and mineral specimens. Common small fragments generally have modest value.
Geological facts
The green color may result from iron in prehnite or nickel in chrysoprase. A diagnostic identification requires hardness, specific gravity, translucency, and ideally microscopy or testing.
Field identification & locations
The reported Townsville-area location favors prehnite or other cavity-filling zeolite-group minerals in regional basaltic rocks, but the specimen could also be purchased or transported. Estimated value: $2–$25 for a small rough piece; $20–$100 if it proves to be attractive, translucent prehnite or quality chrysoprase.
