Lake Ellen Kimberlite Lake Ellen Kimberlite The Lake Ellen Kimberlite is a poorly exposed volcanic breccia located about northeast of Crystal Falls in the Upper Peninsula of Michigan. The first publication in 1981 describing the feature led to speculation that this or similar kimberlites in the area might have been the source of the diamonds discovered a century before in Wisconsin as well as a period of exploration by several minerals firms. The kimberlite was discovered in 1971 when a logging road was bulldozed through the area exposing the unusual looking rock. The exposure consists of several small areas otherwise overlain by glacial
Volcanic rock of most volcanic rocks tends to increase the silica (SiO) content, mainly by crystal fractionation. The initial composition of most volcanic rocks is basaltic, albeit small differences in initial compositions may result in multiple differentiation series. The most common of these series are tholeiitic, calc-alkaline, and alkaline. Most volcanic rocks share a number of common minerals. Differentiation of volcanic rocks tends to increase the silica (SiO) content mainly by fractional crystallization. Thus, more evolved volcanic rocks tend to be richer in minerals with a higher amount of silica such as phyllo and tectosilicates including the feldspars, quartz polymorphs and muscovite.