Granite is an igneous rock with grains large enough to be visible with the unaided eye. It forms from the slow crystallization of magma below Earth’s surface for thousands of years. Granite is composed mainly of quartz and feldspar with minor amounts of mica, amphiboles and other minerals. This mineral composition usually gives granite the varieties of colors from brown, gold, red, pink, gray or white color with dark mineral grains visible throughout the rock.
The word "granite" comes from the Latin word granum, which means a grain.
Marble is metamorphosed limestone, limestone that has been melted and allowed to resolidify. If the limestone is a calcite, then the marble is a calcite marble (i.e., mostly CaCO3); if the original limestone is a dolomitic limestone, then the marble is a dolomitic or magnesian marble (i.e., mostly CaMg (CO3)2).
In nongeological contexts the term marble is often used to refer to any hard, calcite rock that can be cut or polished, including some unmetamorphosed limestones.
Quartzite is a nonfoliated metamorphic rock composed almost entirely of quartz. It forms when a quartz-rich sandstone is altered by the heat, pressure, and chemical activity of metamorphism. These conditions recrystallize the sand grains and the silica cement that binds them together. The result is a network of interlocking quartz grains of incredible strength
Soapstone is a metamorphic rock that is composed primarily of talc, with varying amounts of chlorite, micas, amphiboles, carbonates and other minerals. Because it is composed primarily of talc it is usually very soft. Soapstone is typically gray, bluish, green or brown in color, often variegated. Its name is derived from its “soapy” feel and softness.
Soapstone is often used as an alternative natural stone countertop instead of granite or marble. In laboratories it is unaffected by acids and alkalis. In kitchens it is not stained or altered by tomatoes, wine, vinegar, grape juice and other common food items. Soapstone is unaffected by heat. Hot pots can be placed directly on it without fear of melting, burning or other damage.