|Rock that has been liquefied by heat is ____ (melted).
|A very light, porous, pyroclastic volcanic igneous rock is ____.
|Metamorphic rocks are created by high ____ and pressure.
|The molten rock expelled by a volcano is called ____.
|The minerals diamond and ____ are pure carbon allotropes.
|A very soft mineral (hardness 1) with a greasy feel is ____.
|A common igneous rock in the ____ mantle is peridotite.
|Quartz is a mineral with a ____ crystal structure.