NGT42-3-05
1962
Soggendalite (C.F. Kolderup), a sporophitic dolerite.
42
3
261-268

In his paper on the anorthosites of Egersund (SW-Norway), C. F. Kolderup (1896, pp. 152-159) has given a short petrographic description of the dolerite dikes dissecting the Precambrian basement of that region. He distinguished normal dolerites, so-called bronzitedolerites, olivine-dolerites and, finally, a rock-type called diabasepyroxenite or soggendalite.

Kolderup claimed that this soggendalite differed from the other dolerites by two facts: First, the rock does not have a "typical dia base structure", i.e., there is no continuous meshwork of plagioclase laths. Secondly, the rock was said to consist mainly of clear-red augite in large and allotriomorphic individuals, and of ilmenite, the other components being plagioclase in the form of small laths and a trifle of biotite and apatite. No modal or chemical analysis was given to support the description, but the features of the rock were well illus-ยท trated by a pen-drawing after a thin section (Kolderup, 1896, Pl. Il, fig. 1). To indicate its parental relationship to diabase, as well as its richness in augite, the rock was, first, termed diabase-pyroxenite. But, since pyroxenite is reserved to abyssal rocks, Kolderup proposed to name it soggendalite, after the township crossed by the dike.

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