The Colors Of Granite Depend On The Mineral Grain Size

Quartz is milky white feldspar is white potassium feldspar is pink biotite is black or brown muscovite is yellow and amphibole is green.

The colors of granite depend on the mineral grain size.

Grain size can vary greatly from extremely coarse grained rocks with crystals the size of your fist down to glassy material which cooled so quickly that there are no mineral grains at all. The difference is grain size and cooling rate during the rock formation process. The grain size is coarse enough to allow recognition of the major minerals. Ferromagnesium minerals are dark colored.

Numerous other minerals can be present in granite. Under certain conditions the mineral grains can grow very large. The most common colors of granite are white pink yellow grey and black primarily because of its composition. Coarse grain varieties with mineral grains large enough to see without a magnifying glass are called phaneritic.

When that happens the granite is called a pegmatite. On the other hand if the molten rock is abundant in quartz and minerals that make. The specimen above is a typical granite. Not a problem for rapid cooling of plutons.

Peridotite basalt gabbro diorite rhyolite. The pink grains are orthoclase feldspar and the clear to smoky grains are quartz or muscovite. Trace minerals such as mica and amphiboles also affect the color and composition. But a rapidly cooled volcanic rock with the same composition as the granite could be entirely.

One objection to the earth being only 6 000 years old as described in the bible is the claim that the coarse grained texture of granites shows they cooled slowly over millions of years. Of course diorite and andesite have the same mineral content and occur in the same areas. It is about two inches across. Slow cooling of diorite results into coarse grain size due to large crystals formation with more ion transport.

Granite and gabbro are examples of. If the molten rock was abundant in potassium feldspar the granite is more likely to take on a salmon pink color. The black grains can be biotite or hornblende. The classification of igneous rocks depends on both grain size and silica composition.

For example a granite consists of lots of quartz and feldspar and is generally light colored. The overall color of granite depends largely on the kind of feldspar in the.