igneous

Scoria with Calcite Infills

Vesicular Basalt with secondary Calcification (CaCO3)

Hardness: 5-6 (scoria matrix), 3 (calcite). Color: Reddish-brown to dark grey with white crystalline patches. Luster: Dull/Earthy to Vitreous. Structure: Highly vesicular (honeycombed).

Hardness: 5-6 (scoria matrix), 3 (calcite)
Color: Reddish-brown to dark grey with white crystalline patches
Luster: Dull/Earthy to Vitreous

Identified February 22, 2026More igneous →

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Physical properties

Hardness: 5-6 (scoria matrix), 3 (calcite). Color: Reddish-brown to dark grey with white crystalline patches. Luster: Dull/Earthy to Vitreous. Structure: Highly vesicular (honeycombed).

Formation & geological history

Formed during explosive volcanic eruptions where trapped gases create bubbles; later, mineral-rich groundwater deposits calcite into the vesicles. Secondary mineralization typically occurs thousands of years after the eruption.

Uses & applications

Used in landscaping, high-temperature gas grills, and lightweight concrete aggregate. Mineral specimens are collected for educational purposes.

Geological facts

Scoria is so porous that it can sometimes float on water briefly, though it is denser than pumice. The white streaks are often mistaken for quartz but are usually carbonate minerals.

Field identification & locations

Identify by the distinct bubble-like holes (vesicles) and lightweight feel. Check for white patches that fizz when exposed to weak acid (Vinegar) to confirm calcite presence. Commonly found in volcanic fields.

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