What is Marble and how is it formed?
Marble is a rock composed of recrystallized carbonate minerals, with the maximum concentration of calcite or dolomite. Marble begins life as sedimentary rock known as limestone, which is a soft stone made primarily of calcite. Sedimentary rock is formed at or near the Earth’s surface by the accumulation and lithification of sediment (detrital rock).
Under heat and pressure caused by magma or the tectonic plates, this limestone begins to recrystallize, changing the texture of the rock and causing the calcite crystals to grow and interlock. Most marbles form at convergent plate boundaries. A large part of earth’s crust is exposed to metamorphism. During the process of metamorphism, the calcite recrystallizes that further changes the texture of beige marble. With the progression of the process, the crystals become larger and easily recognizable.
Marble is formed from limestone by heat and pressure in the earth’s crust. The conditions it is put under will cause the limestone to change in its very makeup, as well as texture and appearance, in a process known as crystallization. Large masses of calcite are created when the original carbonate and fossilized materials are recrystallized. And when there are impurities present in the limestone during this transformation, amazing effects and changes take place in the mineral composition. Depending upon the certain temperature, silica impurities react with the carbonate to produce crystals of quartz, or forsterite. At far higher temperatures and with rarer calcium minerals like larnite, other formations are created within the marble. There may also be a variety of other changes, depending on what’s present during the process, including water or other mineral components. Clay, sand, or chert mineral impurities may often produce distinctive veins and swirls within the marble, producing spectacular patterns and discolorations that homeowners and decorators are highly sought after.