Jasper: Jasper is an opaque type of quartz that is red, yellow, brown or green in color.  It is a “chalcedony” which is the name given to compact varieties of silica that comprise minute quartz crystals with sub-microscopic pores.  There are two main varieties of chalcedony:  those that are uniformly colored, and agate, which had bands of differing color.  Jasper breaks with a smooth surface, and like flint, it can be knapped; it can also be highly polished and used as a gemstone.  Jasper was once thought to possess curative powers, as well as to protect against drought.