We understand most clients don’t rock out to geological lessons, but a question we’re often posed with is How does Granite get its Coloration? Granite is one of the worlds most widespread rocks and as a result geography influences the geological attributes of the material. But let’s begin with some key considerations when identifying granite.
Initially rocks are divided into three fundamental groupings; igneous, sedimentary, or metamorphic. Granite is igneous, a rock form that is produced through the cooling and solidification of magma or lava. Two attributes classify rocks as granite. 1) Granite is composed of large mineral grains (this influenced the Latin name, granum, or grains that fit together). Granite is a phaneritic, which means the individual grains are large enough to be identified and distinguishable by the human eye. 2) Within the rock there is a commonality of minerals, predominantly quartz and feldspar. A abundant rock on earth, granite is often found in mountain ranges like the Rockies and is located in huge masses referred to as batholiths, which form the roots of mountains.
Granite primarily is composed of quartz, potassium feldspar, sour plagioklaz, and mica. Due to differing amounts of these compounds, granite comes in naturally occurring variations of color. Coloration is primarily dependent upon the mineral composition of feldspar which strongly influences the decorative flourishes found within the stone. Most prominently found as grey (due to common feldspar), unique variations can include black, dark-red, and rarer green and blue hues. The bulk of the granite is typically lighter grey and is punctuated by the darker secondary minerals. As a result, the most common form of granite is often described as salt and pepper in appearance. Texture is often evaluated in granite to determine its commonality or exotic composition. The individual minerals in granite grow into visible grains as the magma cools slowly, creating an uneven speckled appearance.
A general guide for granite coloration identifies quartz as providing clear, pink, or black granules. Amphibole produces shades of black and brown, and potassium generates green. Feldspar comes in a wide variety of types including common feldspar for white and grey, and K feldspar for blue, black, pink, or sometimes vibrant yellow. Red and pink Feldspar color true to their names, and mica provides grains of black.
Within the Okanagan, Phoenix Ridge tends to reveal granite with blue and brown coloration. This unique speckling of blue and brown is due to several factors, including water running through the seams, forest fires and aging of the rock. The wall rock or buildstone that is pictured above is mostly brown with speck of blue. Once said rock is crushed it is mostly a blue/grey color with only specks of brown. (is this enough information?)
If you’re looking for a unique piece of the Okanagan, shaped by our geography and geology call Phoenix Ridge Quarry at 250 826 3175.