Igneous Rocks
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OBSIDIAN DESCRIPTION: Called nature’s glass, glassy smooth volcanic rock. Breaks with a sharp conchoidal fracture. Formed during slow cooling of lava. ORIGIN: Washington State, USA |
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The color or obsidian is determined by the chemical makeup of the lava. When there are white splotches in black obsidian, it is called "snowflake obsidian". |
| PUMICE igneous DESCRIPTION: This is a light, porous rock. When volcanoes erupt, lava froths and hardens into rocks that have many holes in it. ORIGIN: USA COLOR(S): dark, brown COLOR DISTRIBUTION: uniform |
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BASALT igneous DESCRIPTION: Fine grained matrix filled with gas bubbles that have been filled in with minerals. Formed during rapid cooling of lava. ORIGIN: Nova Scotia COLOR(S): medium dark brown host rock with green, white pink COLOR DISTRIBUTION: speckled with white & green spots |
Internal Volcanic