Silkstone is a classic lapidary material originated from the Cuyuna Range. Unfortunately Binghamite and Silkstone were mixed up today.
But there are differences in their appearence: Binghamite is showing a parallel arrangement of its fibers, often along a larger distance (within the cm range). As consequence, the rough rock must be orientated correctly: the elongation of the fibers must be appropriate parallel to the view sideof the cabochon. Each inclination to this ideal line produces a lacking in the quality of the Chatoyance. This is different to the Silkstone, whose fibers shine up usually wavelike, similarly like combed curls through the stone. So the growth of the fibres permits different cutting positions for the production of beautifully chatoying cabochons. Binghamite is usually more intensively colored than Silkstone, whereby one can award both the colours yellowish, brownishly, reddish and easily greenish. Binghamite occurs usually as smaller inclusions in quartz, while Silkstone even in larger monomineralic boulders on the dumpsof the Cuyuna Range was found. Silkstone is bearing more iron oxides, mostly as goethite. Since the heydays of the iron mining industry in the Iron Range are gone, these gemstone-materials became rarities.