Color and veining of natural stone

Veining
Since ancient times, natural stones have added a sense of grandeur to palaces, cathedrals, civic buildings and living spaces all over the world. These stones contain natural veining and color that enhances their uniqueness and attraction.
In geological terms, veins are the finite volumes within stones, having distinct shapes and filled with crystals of minerals which were precipitated from fluids. Due to hydrothermal circulation, fluids carrying mineral constituents form veins into a stone mass. Two types of mechanism- open-space filling and crack seal growth causes veins to be formed in stones and they are the result of growth of crystals on the walls of planar fractures in stones.
Veining in stones varies from soft to hard and soft veins are more susceptible to damage. Wet and damp areas are not suitable for stones that have softer veining as the minerals in them might slowly disintegrate and streaks and color variations occur. Some marbles Crème Marfils, Perlino Rosata, Breccias have this kind of problem. Hence, it is important to select the right stone for the right place according to the quality of veining.

Color
The beauty of natural stones lies in their distinctive nature. No two stones are the ever same as each piece of stone has its own natural characteristics such as color, veining and markings, as well as hardness and porosity. The opulent, intensity and array and combination of different colors greatly enhance their visual appeal, although some shades have greater color variation than others.
Stones contain different minerals like dolomite, calcium, quartz; feldspars etc. and these colorless minerals when combined during several stages of stone formation create this kaleidoscope of color of stones. Any kind of light, especially sunlight can really reflect the true color of a particular stone and some stones have distinct respond when exposed to different shades of light. When wet, the colors are brought to life. Modac, especially, looks wonderful in the cool English light of winter when soft landscaping is fading into its autumnal and wintry state. It is a shade to choose if you want to bring a warm Mediterranean appearance to your garden
As stones contain lots of minerals, the color of a stone might change or fade due to natural weathering and use of harmful chemicals.
I) Natural Cause: Nothing is eternal, more so for natural stones. The natural weathering process and the ultraviolet rays from the sun and improper care of your stone may cause the color of stones to fade slowly. Limestone and black marbles are examples.
ii) Chemical Cleaning: some manufactures use acid in there cleaners. But some stones are very sensitive to acids and alkaline cleaning solutions and excessive use of them cause fading effect on stones. So you must be careful not to use too much of acidic or alkaline solutions on natural stones.
iii) Sometimes, the optical qualities of natural stones can be changed by etching their exposed mineral surfaces.