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 ...

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.

In some cases, amethyst crystals can grow to impressive sizes, filling entire geodes with their vibrant purple hues. Amethyst is found in a variety of geological settings, but it is most commonly ...

Thundereggs specifically form in rhyolitic lava. Rhyolitic lava flows ... Geodes typically have a hollow cavity lined with crystals. They form in sedimentary rocks like limestone, where mineral ...

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 ...