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Memorias de la Sociedad Cientifioa 



as desired. Although every variety shows fine graduations of 

 color and handing, we remark principally: Orange-onyx of the 

 most wonderful kind produced at the deposits of "Pozo de 

 Calvo"and"LasViboras;" amber-onyx of fine yellow colour, 

 found in "Las Viboras;" Rose-ban ded-onyx, remarkable for 

 delicacy of tones and curiously striped; Jasper-onyx or black 

 onyx, banded white and black, with variegated figures; Agate- 

 onyx, and many kinds of clouded onyx, white, red and some- 

 times green like onyx coming from Puebla and Oaxaca quar- 

 ries. , 



The structure of onyx marble is holocrystalline, common- 

 ly fibrous or columnar, rarely-granular and scaly; semi-trans- 

 lucent, increasing by transparency the intensity of colour. The 

 composition is absolutely similar to that of so called onyx 

 marble from other countries, i. e. carbonate of lime (more than 

 90 p§ ) with very little sulphate of lime and carbonate of iron 

 and other impurities. 



Hardness 3 Weight of cubic meter .... 2.71 tons. 



Specific gravity. 2.71 „ „ „ foot 78.5kilos=1731bs. 

 I have already indicated that the topographical condi- 

 tions, and position of these deposits give plenty of facilities for 

 working, and allouringfor the establishment of a plant of" ma- 

 chinery of any capacity desired. In a very dry country as this 

 is, we fix first on the question of water supply. Water, is not 

 very deep in the valleys near the deposits, also at the foot of 

 the mountains, where we made the necessary investigations to 

 assure the existence of an underground level not far from 50 

 to 60 feet in depth. Fuel would be transported from the rail- 

 way either at Peralta or Noria Station. Good workmen are 

 plenty in the small towns and Jimulco. The customary wages 

 being one dollar silver per day. At Jimulco provisions etc. can 

 always be obtained and implements can be brought from To- 

 rreon on the Central R. R, four hours travel from Jimulco. 

 As is well known, the Central R. R. is connected at El Paso 



