Marble and granite are 100% all natural stones.
Granite is an igneous rock, formed from the extraordinarily slow crystallization of magma deep beneath the surface of the Earth. Granite is predominantly composed of the minerals quartz and feldspar, with smaller amounts of mica, amphiboles, and other minerals fused within the composition. The variances in the mineral components influence the color and pattern of each individual granite slab mined from a quarry. Marble is a metamorphic rock, formed from the heat and pressure of metamorphism applied to limestone, when the mineral calcite recrystallizes to form a rock comprised of interlacing calcite crystals. The same process occurs when the mineral dolomite recrystallizes to form a rock comprised of interlacing dolostone crystals. Marble contains other minerals including clay minerals, micas, quartz, pyrite, iron oxides, and graphite. Marble is usually a light-colored rock. When it is formed from a limestone with very few impurities, it will be white in color. However, marble containing impurities such as clay minerals, iron oxides, or bituminous material can be pink, yellow, bluish, grey, or black in color.
Quartz, however, is partially man-made.
Where nature has created the quartz mineral which comprises 90% of quartz countertops, it is combined with resins, polymers, and diverse types of pigments to form the finished product. Because quartz countertops are engineered stone countertops, they form a hard stone-like countertop much like granite. Quartz countertops appear differently due to how the quartz is ground. If it is ground into a fine powder, it will have a smooth appearance. Conversely, if quartz is ground coarsely, it will have a flecked appearance.