James Orton,
Underground Treasures: How and Where to Find Them
“ The object of this work is to point out those distinctions so clearly and in popular language that those who do not claim to be scientific may determine specimens for themselves; in other words, to furnish a key for the ready determination of all the useful minerals within the United States. [1] Two hundred and forty-four mineral species have been found within the bounds of the Union. Of these only one-third are of any use to the practical man. ”
