In this case, the material is microscopic crystals of metallic magnetite ... origin is what classes rainbow obsidian as an igneous rock. Lava destined to become obsidian cools rapidly once ...

In general, mineral particles are small, having formed within confined areas such as lava flows or between grains of sediments. Large crystals found in geodes and other rocks are relatively rare.

The lava has a thin crust on it that's caused by air cooling, so the geologist has to break this with his rock hammer before taking a sample. Lava sampling regularly happens at Kīlauea Volcano to ...

An curved arrow pointing right. Adding relatively minor factors like crystals, water, ice, and metal can drastically affect how lava moves, cools, and creates formations. When lava meets water ...

Magnitude-3.4 at 12:46 a.m. March 11 at 10 miles southeast of Pāhala and depth of 20 miles. Magnitude-3.4 at 4:08 p.m. March ...