How Do Extrusive Rocks Form?

Answer Extrusive rock is one of two types of igneous rock that comprise more than 90 percent of the Earth's upper crust. Born in the heat and pressure far below the Earth's surface, extrusive rock begins ... Read More »

Top Q&A For: How Do Extrusive Rocks Form

Are pumice rocks intrusive or extrusive?

Pumice is a type of intrusive rock. It begins life as granitic lava that cools very quickly, becoming pumice. Most pumice is formed in eruptions that have high gas content, causing the pumice to ha... Read More »

How do crystals form in rocks?

Crystals form in rocks that have been heated to such a high degree deep within the earth that they actually melt. When these rocks cool down, crystals form.Molten RockCrystals in rock have usually ... Read More »

What Type of Rocks Can Form From the Process of Weathering & Erosion?

Mechanical and chemical weathering combine to attack any rock surface. The debris that builds up is often transported by wind or water erosion to a depositional basin where layer after layer accumu... Read More »

Can I use a household drill on polished quartz rocks, sunstones, and sodalite rocks?

You'll need a diamond drill bit, something to pour water over the stone while you drill to keep the bit cool, and some sort of jig to hold the stone in place while you drill.