Schoolcraft, the expedition's official geologist, explored further and speculated on the region's mineralogy:
"Still detained by head winds. In loitering along the shore of the lake, examining the loose stones, I discovered in a detached block of mica slate, several large and well defined crystals of staurotide, of a dark reddish brown colour, moderate hardness, and perfectly opaque. Near the same spot a number of petrifactions (celleporites and madreporites) were observed in the detached fragments of limestone, found along the coast; but what excited a particular interest, was a large block of granitic rock imbedding globular pebbles of hornblende. This rock, as being a quarternary compound of feldspar, quartz, mica, and hornblende, would be considered a granilite according to the suggestions of Kirwan. The masses of hornblende, which are in most instances pure and unmixed, in others contain feldspar and quartz, thus indicating a transition of one substance into the other which does not admit of a ready explanation. Will the present state of mineralogical science, justify us in considering this substance as a primitive breccia? or its a granitic porphyry?"
Location: near modern Port Hope, Mich.
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