Igneous or Sedimentary?

• Obsidian is an igneous rock that is black, glassy, and breaks like glass.
• It forms from rapid-cooling lava that has a lot of silica and does not have time to form crystals.
• Limestone is a sedimentary rock that is usually white, gray, or tan and may contain fossils.
• It forms from a chemical reaction in seawater that makes lime mud that sinks to the bottom of the limestone.
• Basalt is an igneous rock that is dark gray to black, fine-grained, and hard.
• It forms from a magma rich in iron and magnesium and poor in silica, which erupts from a volcano or fissure.
• Diorite is an igneous rock that is medium to dark gray, coarse-grained, and dark-colored.
• It forms deep in the Earth's crust from cooling magma that does not contain a lot of quartz or light-colored minerals.
• Dolostone is a related rock to limestone that is composed of the mineral dolomite and does not fizz with vinegar.
• Basalt may contain gas bubbles and is sometimes called vesicular basalt.

Test your knowledge on different types of rocks with this engaging quiz! From the black and glassy obsidian to the fine-grained basalt, learn about the unique characteristics and how they form. Discover the difference between limestone and dolostone and find out why basalt is sometimes called vesicular basalt. This quiz will challenge your geology skills and expand your understanding of the fascinating world of rocks.