CORUNDUM (RUBY): OCCURRENCE IN THE UNITED STATES 279 



I'ubies in the IMacdonnell Ranges of the Northern Territory of South Australia was reported. 

 No less than twenty -four companies were very shortly formed for the working of the deposits. 

 A more thorough examination of the stones, however, showed them to be red garnets, of fine 

 quality, but compared with the true ruby almost valueless. These same garnets are now 

 sometimes sold as " Adelaide rubies."" 



The United States of North America yield a few rubies, occurring rarely associated 

 with common corundum, which is very abundant in this country. In the Lucas mine on 

 Corundum Hill in Macon County, North Carolina, small amounts of transparent red 

 corundum, sometimes suitable for cutting, have been found. The boss of serpentine which 

 forms the main mass of Corundum Hill is traversed by large veins of common corundum. 

 Rubies of much better quality have been found more recently in Cowee Creek, also in 

 Macon County, about five miles from Franklin, and have been described (1899) by Professor 

 J. W. Judd and Mr. W. E. Hidden. These authors point out that there are three distinct 

 modes of occurrence of corundum in North Carolina and the adjoining States : 



(1) In the ordinary crystalline schists and gneisses of the district, as long prismatic 

 crystals usually of a purplish tint and not of gem quality. 



(2) In the olivine-rocks, and the serpentine derived from them, which are intrusive in 

 the crystalline schists, as crystals often of large f^ize and showing great variety of colour, 

 but seldom or never clear and translucent. 



(3) In certain garnet-bearing basic rocks at Cowee Creek, as small tabular and short 

 prismatic crystals, which frequently exhibit the transparency and colour of the " oriental 

 ruby." 



These garnet-bearing basic rocks include eclogite, amphibolite, and other similar rocks 

 of igneous origin. They have been much weathered, however, and are represented solely by 

 a soft decomposition product known to American petrologists as " saprolite.'" In this 

 material the rubies occur in " nests " and " bands," and also in what appear to have once 

 been cavities in the original rock. These cavities, when the corundum is pale coloured, 

 appear to have been filled with felspathic material ; but when the corunduu) is of a ruby- 

 red colour, the surrounding space is filled up with chloritic material. The associated 

 minerals are garnet, in great abundance, sillimanite, kyanite, staurolite (often very clear 

 and gem-like in character), cordierite, zircon, monazite, and others, together with minute 

 quantities of gold. 



The corundum found here varies in colour from ruby-red through different shades of 

 pink to white. Many of the red crystals exhibit the beautiful so-called pigeon's-blood tint, 

 and are in no way inferior to the finest Burmese rubies. Enclosures of various kinds are, 

 however, frequent; these may bs extremely minute (" silk" of jewellers), giving rise to a 

 cloudiness (" sheen ") in the faceted gems, or they may be larger reniform masses of clear 

 red rutile or black ilmenite. Some crystals of ruby have been found to enclose crystals of 

 the newly discovered variety of garnet known as rhodolite, to be described in its appropriate 

 place. Enclosures of this kind, however, in no way impair the transparency and beauty of 

 the ruby. Some few specimens of ruby have been found perfectly free from enclosures and 

 large enough to give a cut gem of very fair size. 



Although the Cowee Creek rubies are very like Burmese stones, yet their mode of 

 occurrence is totally different, for in the former locality the white crystalline limestone of 

 Burma is absent, as are also the fine red spinels so characteristic an associate of the rubies 

 of Burma. 



In the State of Montana a few rubies have been found in association with sapphire ; 

 they are usually of a pale rose-red colour like those of Ceylon, stones of a fine deep colour 



