'Antonio Álzate." 383 



ble but always large £rom ten to one hundred feet, about 

 twenty-five feetbeiugthemost comrnon. Some croppings run 

 without aii}^ interruption for several hundred feet (from 600 

 to 1500) and so cióse are tlie deposits or grottes one to the 

 other as to admit o£ niany being worked by only one quarry. 



The deposits on the road to Caencamé ave very numerous 

 and cióse together. One group covers an areaof two hundred 

 acres, there being besides many others separated enough to 

 be considered apart. Less extensivo are the deposits east of 

 the railway bul? also extensivo enough to admit work of any 

 capacity. In the barranca de "Las Víboras," four miles from 

 Noria Station, one of the pockets should give with a little ex- 

 pense more than 200,000 cubic feet, considering only the su- 

 perficial deposits. Some of those of Pozo de Calvo, three mi- 

 les from Noria, should give also many thousands of cubic feet 

 on the surface of good onyx in very large pieces. 



The position of deposits on the flanks of the mountains 

 near or at the base and on the slopes of the hills is also wor- 

 thy of notice. Croppings rise up to the general rocky surface 

 which f acilitates the opening of quarries without much barren 

 work and obtaining good proflt from the beginning of work. 

 The fissures that sepárate the blocks or tablets of onyx in 

 some of the deposits are almost vertical and this renders easy 

 their extraction, giving pieces with mínimum thickness of 

 fifteen inches. The common size of blocks that can be got 

 here i.s similar to that of other onyx deposits of México, afair 

 average could be placed at twenty inches thick by four feet 

 broad and five feet long. Very often blocks larger than thirty- 

 five cubic feet are encountered. I saw in the small prospec- 

 ting works of "Las Víboras," enormous pieces, several of five 

 tons weight, of onyx marble of splendid honey-yellow colour. 



We cut from various places many samples in order to have 

 some idea of the very many diíferent coloured varieties of onyx 

 and in some deposits, of these as large pieces can be obtained 



