A nicely arranged example of fluorite with quartz, from Erongo.  The matrix is a mixture of quartz and schorl tourmaline with a number of green fluorites (some with brown cores) scattered around a central quartz crystal.  As is typical for Erongo fluorite, it does need strong lighting for the color to be appreciated-- the ones near the edges light up particularly well. In order to display better, some of the back has been carved away as well to help light pass through.