68 Scientific Intelligence. 



associated ; indeed the passage of rocks consisting of various 

 silicates with a few calcite crystals into masses principally com- 

 posed of calcite, but with the silicate minerals and oxides dis- 

 persed through them, is of the most insensible kind. Some of 

 the ruby-bearing limestones are highly micaceous (" cipollinos "), 

 others are " calciphyres," in some of which the individual calcite 

 crystals attain enormous dimensions. With the rubies and 

 spinels are found a great number of oxides and silicates, both 

 original and secondary, with much graphite and pyrrhotite. 



In the gravels and clays of the district fine specimens of the 

 minerals derived from the atmospheric degradation of the lime- 

 stones and other rocks are found, sometimes broken and water- 

 worn, at other times almost uninjured. 



The study of the extensive series of minerals brought from the 

 ruby mines of Burma is calculated to throw light upon many 

 important scientific problems. 



The association of minerals in the remarkable crystalline lime- 

 stones of Burma is worthy of the most careful consideration. 

 Corundum — in its various forms of ruby, sapphire, white sapphire, 

 oriental amethyst, oriental topaz, etc. — is found associated with 

 red, purple, brown, black and other spinels, the relative propor- 

 tions of the minerals composed of aluminium oxide and^ of mag- 

 nesium aluminate being very variable. The other minerals 

 present in the crystalline limestones are zircon (rare) ; garnets 

 (abundant in some places) ; a remarkable blue apatite ; feldspars, 

 of many species and varieties (including murchisonite, moonstone, 

 sunstone, etc.), and in every stage of alteration; quartz (in many 

 varieties, and exhibiting some remarkable peculiarities of crystal- 

 lization) ; micas (phlogopite, fuchsite, with muscovite and other 

 secondary and so-called hydromicas); hornblende and arfved- 

 sonite ; augite (sahlite, diopside, and segyrine) ; enstatite (bronzite 

 and hypersthene) ; wollastonite ; lapis-lazuli ; fibrolite ; scapolite ; 

 with graphite and pyrrhotite. In addition to muscovite and other 

 secondary micas, we find the following alteration products : 

 Diaspore, margarite, and other clintonites, chlorites, vermiculites, 

 and carbonates. 



It is a noteworthy circumstance that none of the silicates com- 

 bined with fluorine and boron compounds — such as topaz, tourma- 

 line, chondrodite and humite, axinite, or datholite have been 

 certainly detected in these limestones. Beryl (aquamarine) and 

 danburite have been said to occur in the ruby earths, but there is 

 reason for doubting the correctness of the statement. The lime- 

 stone which, in the association of minerals found in it, most 

 closely resembles the rock of Burma, is the remarkable white 

 limestone of Orange County, N. Y., and Sussex County, N. J. ; 

 but in the American rock the corundum and spinels are associated 

 with tourmalines and chondrodites. 



In considering the question of the origin of the corundums and 

 spinels of Burma, there are several very important facts to be 

 borne in mind. The gems, when found in situ, always appear to 



