Quartz (crystalline SIO2) is the most abundant mineral in the Earth's continental crust.
Quartz is made up of a lattice of silica (SiO2) tetrahedra. Quartz has a hardness of 7 on the Mohs scale and a density of 2.65 g/cm³.
Pure quartz is colorless or white, colored varieties include rose quartz, amethyst, smoky quartz, milky quartz, and others. Quartz goes by an array of different names. The most important distinction between types of quartz is that of macrocrystalline (individual ...
Volcano Calendar 2019 We're proud to present our 2019 volcano calendar: 13 different and attractive images of volcanoes, volcanic landscapes and phenomena taken during volcano tours over the past few years.
The subplinian eruption of Kelut volcano Fascinating satellite images, reports, and pictures about the massive explosion of Kelut volcano in East Java on 13 Feb 2014.
Worst earthquakes of the 20th century More than 1.5 million people lost their lives because of earthquakes in the 20th century. Check the list of damaging and deadly quakes from 1900-1999!
