p. 118

128

Mineralogy

The following is an enumeration of the minerals heretofore found in this Territory, so far as they are known to the author, but it undoubtedly falls very far short of the actual number. So large a portion of our territory has never been visited by any mineralogist that we may not be surprised to learn hereafter of the existence of many rare and valuable minerals not now known to exist here.

Sulphuretted Hydrogen: Several sulphur springs have been noted by the surveyors of the public lands, which are probably springs whose waters are impregnated with this gas.

Bitumen, occurs in small cavities in the limestone along the shore of Lake Michigan both liquid and solid. The liquid variety, is known as Petrolium or Seneca oil, has not however been found in sufficient quantity to be collected for medicinal purposes. It appears to result from the animal matter of the petrifactions found in the rock.

Graphite- or Black Lead was found by Schoolcraft at the Grand Portage on the St. Louis river. It was however of inferior quality; it formed a vein between the vertical layers of argillite

73