386 SERPENTINE AND GREENSTONE. 



modification of the primitive mica-slate of Maniquarez, 

 containing garnets, cyanite, and rutile titanite. These 

 insensible passages from primitive to transition strata, by 

 clay-slate, which becomes carburetted at the same time that 

 it presents a concordant position with mica-slate and gneiss, 

 have also been observed several times in Europe by cele- 

 brated geologists. The existence of an independent for- 

 mation of primitive slate (urthonschiefer), may even be 

 doubted, that is, of a formation which is not joined below 

 by strata containing some vestiges of monocotyledonous 

 plants. 



The small thonschiefer bed of Malpasso (in the southern 

 chain of the littoral Cordillera, is separated from micaslate- 



fneiss by a co-ordinate formation of serpentine and diorite. 

 t is divided into two shelves, of which the upper presents 

 green steatitous slate mixed with amphibole, and the lower, 

 dark-blue slate, extremely fissile, and traversed by nume- 

 rous veins of quartz. I could discover no fragmentary stra- 

 tum (grauwacke), nor kieselschiefer nor chiastolithe. The 

 kieselschiefer belongs in those countries to a limestone 

 formation. I have seen fine specimens of the chiastolithe 

 (macle), which the Indians wore as amulets, and which 

 came from the Sierra Nevada de Merida. This substance is 

 probably found in transition-slate, for MM. Bivero and 

 Boussingault observed rocks of clay-slate at the height of 

 2120 toises, in the Paramo of Mucuchies, on going from 

 Truxillo to Merida.* 



III. FORMATION op SERPENTINE AND DIORITE (&REEN- 

 STONE OF JUNCALITO.) We have indicated above, a layer 

 of granitiferous serpentine inclosed in the gneiss of Buena- 

 vista, or perhaps superposed on that rock ; we here find a 

 real stratum of serpentine alternating with diorite, and ex- 

 tending from the ravine of Tucutunemo as far as Juncalito. 

 Diorite forms the great mass of this stratum ; it is of a dark- 

 green colour, granular, with small grains, and destitute of 



* In Galicia, in Spain, I saw the thonschiefer containing chiastholite, 

 alternate with grauwacke ; but the chiastholite unquestionably belongs also 

 to rocks which all geologists have hitherto called primitive rocks, to 

 mica-schists intercalated like layers in granite, and to an independent 

 stratum of mica-slate. 



