This linear formation (vein) of quartz which formed underground is probably a result of seepage of water and chemicals into crevices in the bedrock. Erosion has now exposed it to the surface.
Quartz is an igneous rock made out of molecules of silicon and oxygen atoms held together in a crystal pattern. It is a major constituent of many rocks and make up approximately 14% of the earth’s crust.
Quartz occurs in virtually every color. Common colors are clear, white, gray, purple, yellow, brown, black, pink, green, red.