Rocks are naturally occurring solids which are composed of minerals & have been used by humans since ages. From Stone Age, rocks are used for various purposes. Also, the metals and minerals found in rock play an important role in our life. Get to know all the Variolite Uses. We have provided you with all information about Variolite rock here. Variolites are a group of dark green basic igneous rocks which exhibit pale colored spots, or spherules, especially on weathered surfaces, that give them a pockmarked appearance. Variolite is available in black, brown, light to dark grey colors. The streak of a rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Variolite is white to grey. Get to know more about Variolite rock and characteristics of Variolite rock in the next sections.