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Ch. 9: The Feldspar Group, including Amazonite, Moonstone, Sunstone, etc.

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GEMS AND PRECIOUS STONES
163
 
 

 
 
the blue chatoyancy remarkably well. It is there called "moon­stone," and may well be classed under this head, for it has the chatoyant effect and in appearance differs but slightly from ortho-clase moonstone. The greenish-gray granular albite or oligo­clase found in the serpentine at the magnesia quarries, West Nottingham Township, Chester County, Pa., shows a faint blue moonstone lustre. The beautiful feldspar found by W. W. Jef-feris.with the sunstone at Pearce's paper mill, shows a blue chat­oyancy as marked as that of any labrador spar. It may be the latter, or perhaps oligoclase. The finest examples of this mate­rial, very closely resembling that from Ceylon in quality, trans­parency, and color, and forming gems 1/2 inch across, have been found at the Allen Mica Mines, Amelia Court House, Va. It also occurs in opaque pieces 6 to 8 inches square and of good color, showing a delicate blue chatoyancy. Crystals an inch in length, of an opaque adularia feldspar, showing a beautiful blue chatoyancy, are found on Mount Beckwith, Col. Very good sunstone oligoclase, with fine reflections, has been found near Fairfield, Pennsbury Township, Pa., also at Mendenhall's lime quarries, Pennsbury, Chester County, and in Ashton Township, Pa., some of a grayish-white colorwith coppery reflections ; and a curious variety in moonstone (albite), showing double reflections. The green and red sunstone found near Media, Pa., is very fine. In Middletown Township, Delaware County, Pa., in one local­ity moonstone and sunstone in small nodular lumps are scattered through the soil, and about a ton of the material has been re­moved since its existence was discovered; in another locality in the same township, moonstone is found in boulders. A very fine sunstone, the orthoclase of which is of a rich salmon color, quite transparent and streaked with white, showing the aventur-ine effect beautifully, is found at Glen Riddle, Delaware County, and another beautiful variety in the hornblende at Kennett Town­ship, Chester County, Pa. ; this Professor Genth thinks is probably an oligoclase. Greenish orthoclase, sometimes in bright green pieces, also pale green, and at times spotted with brownish tints, all showing a sunstone effect, is found at Mineral Hill, Middletown, and Upper Providence, Delaware County, Pa. The orthoclase of Frankford, Pa., with gothite disseminated
 
 

 
       
Ch. 9: The Feldspar Group, including Amazonite, Moonstone, Sunstone,  etc. Page of 364 Ch. 9: The Feldspar Group, including Amazonite, Moonstone, Sunstone,  etc.
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