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 Tephrite Uses. We have provided you with all information about Tephrite rock here. Tephrite is an aphanitic to porphyritic textured, volcanic igneous rock. Tephrite is available in black, brown, colourless, green, grey, white colors. The streak of a rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Tephrite is bluish black. Get to know more about Tephrite rock and characteristics of Tephrite rock in the next sections.