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Sec. III, Ch. 1: The Ruby

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154                                  The Ruby.
of crystalline and saccharoidal limestone. The structure of the country has been described by Mr. C. Barrington Brown, whilst the petrology of the Ruby rocks has been carefully worked out by Prof. J. W. Judd, C.B. The matrix, or parent rock of the Ruby seems to be the lime­stone, which in some cases is boldly crystalline and in others finely granular. With this limestone are associated certain basic rocks, such as those known technically as pyroxenites and amphibolites. It is suggested by Prof. Judd that the. limestone has probably been produced by the metamorphism of the lime-bearing felspars in the basic crystalline and foliated rocks. The felspar may be first altered to scapolite; and from this rather unstable mineral, carbonate of lime may eventually be formed ; at the same time the aluminium silicates of the felspars, being decom­posed by natural acids, have suffered decomposition, with final production of alumina. This alumina, under certain conditions of temperature and pressure—the latter being apparently very great—has crystallized out as corundum, which takes exceptionally the condition of Ruby. The Ruby is thus found, with other minerals, embedded in the limestone as a matrix.
By the disintegration of the matrix, the Rubies and Spinels have been set free ; and are now largely found, as rolled crystals and derivative fragments, among the detrital matter which is abundantly distributed over the valleys, along the hill-sides, and on the floor of the limestone-caverns. A brown or yellowish clay, known locally as Byon, seems to be the typical Ruby-bearing earth.
In 1887, when working the mines, and before the Com­pany was formed, the author obtained from Burma a curious rough Ruby, weighing 49 carats, and consisting of a flattened aggregate of ill-defined crystals. Between
Sec. III, Ch. 1: The Ruby Page of 366 Sec. III, Ch. 1: The Ruby
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