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UNITED STATES, CANADA AND MEXICO
197
With the malachite at Copper Queen Mine is a variety which has proved on examination to consist of equal parts of carbonate of lime and carbonate of copper. This is slightly harder than malachite, and the name, calcomalachite, indicating its composition, has recently been suggested for it. Like mala­chite, it admits of a fine polish and is susceptible of similar uses.
A beautiful compact chrysocolla, mixed with quartz, is found at the Allouez Mine, Houghton, Lake Superior region. Some of the specimens would furnish fine, rich, bluish-green gems half an inch square. Specimens of chrysocolla from the Cop­per Queen Mine, Ariz., coated with quartz and chalcedony, fur­nish beautiful gems when the polish on the layer of quartz chalce­dony is thin enough to allow the chrysocolla to show through. In one case, these markings resembled a human head.
Aragonite (carbonate of lime) or "satin spar," from near Dubuque, Iowa, especially that from Rice's Cave, and in the re­markably fine forms known as the " floss ferri " variety, from near Rapid City, Dak., would admit of the same uses as com­mon satin spar. The satin spar gypsum or sulphate of lime, while made so extensively into ornaments and sold at Niagara Falls and many tourists' resorts, is, almost without exception, im­ported from Wales, though some few of the common white gypsum ornaments sold at Niagara are cut from the gypsum found in the vicinity. On Goat Island large masses of gypsum are found, and occasionally even under the Falls, where the ma­terial for all the ornaments sold there is supposed to be found. Beautiful selenite occurs there, but no satin spar.
The dark amber-colored and brown aragonite (California onyx) from California is extensively used as an ornamental stone, but not as a gem stone. Many thousands of dollars' worth are annually used by marble workers and for decorative purposes.
In the Luray and other American caves are found calcare­ous concretions called cave pearls, which consist either of pieces of stalagmite worn round by falling water or of similar pieces forming nuclei on which successive layers of carbonate of lime have been deposited.