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 Essexite Uses. We have provided you with all information about Essexite rock here. Essexite which is also known as nepheline monzogabbro, is a dark gray or black holocrystalline plutonic Iigneous Rock. Essexite is available in dark grey to black colors. The streak of a rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Essexite is black. Get to know more about Essexite rock and characteristics of Essexite rock in the next sections.