EXPERIMENTS RELATIVE TO METEORITES. 335 



crvstallino peridot ;* it is identically the same product yielded by llierzolite. 

 Itslionld be remarked, however, that when serpentine is melted, without any 

 addition, in a crucible, it cannot fail to take up from the walls of the latter some 

 uf hs elements, and particularly silex. 



In these fusions, as in those of meteorites, the tendency which the peridot and 

 enstatite have to crystallize causes them to appear in very distinct crystals ; l)ut 

 tlie product obtained includes, moreover, other silicates, aluminous or otherwise, 

 which remain intimately intermixed, and, as it were, dissolved in the interior of 

 the former. 



These various results, the last especially, show that serpentine has often a 

 decided tendency to change into peridot, as if it then only entered into its normal 

 state. This is a reason the more for considering serpentine, at least in a certain 

 number of its repositories, as a peridot or a Iherzolite which has lost a certain 

 quantity of its magnesiuni, and has become hydrated, by an operation which 

 recalls that of the conversion of feldspar into kaolin. 



The direct observation of rocks confinns this conclusion. On the one hand, 

 there exist Iherzolites which graduall}' degenerate into serpentine, as is ol)served 

 in certain localities of the Pyrenees ;t at Brezouars, in the Vosges ;| at Neurode, 

 in yilesia; and in the rock known by the name oi schillerfcJs or basiife'm Tran- 

 8ylvania,§ in Nassau, and elsewhere, j] On the other hand, there are serpentines 

 which manifest as clearly their relation with theperidotic rocks. A more demon- 

 strative instance of this lact cannot be seen than in the serpentine of Baldissero, 

 of which 1 have already spoken. One of the varieties of this serpentine per- 

 taining to the collection of the Museum, where it was placed by M. Oordier, per- 

 fectly recalls, in its external characters, the Iherzolite of the Pyrenees. 1 have 

 recognized, moreover, that, like the latter, it is interspersed with crystals of ensta- 

 tjte of the bronzite variety, with pyroxene diopside of an emerald green and 

 chrtimiferous, as well as with black chromiferous spinelle, sometimes in regular 

 octahedrons, (variety called picotite.) These three mineral species present iu 

 both rocks exactly tlie same facies. Yet, ncjtwithstanding these analogies, the 

 serpentine of Baldissero is distinguished from Iherzolite by its imperfect hardness 

 and its persistency in water; it constitutes, as it were, one of the states of tran- 

 sition of the iirst rock to the second. The minerals which have resisted hydra- 

 tation remain as witnesses of the primitive state, in such sort that the relation of 

 kaolin to feldspar is not better demonstrated than the transformation which we 

 arc Considering. 



There is nothing to prove that the hydratation which has been produced in 

 the transformati(jn of peridotic rock into serpentine was ellected by agentnes on 

 the surface of the globe. The eruptive serpentine of the Apennines, the Alps, 

 and of so many diil'erent countries, may have been ejected from below alter hav- 

 ing already acquired the water which it contains to-day. The manner in which 

 glass is decomposed iu water super-saturated with heat and is changed into a 

 hydrated silicate, as I have veriiied in former experiments,^ would not seem to 

 be without analogy with the reaction which may have produced the serpentine 

 at the expense of ^)re-existent anhydrous silicates. 



Not that 1 would pretend, however, that all serpentine masses result from tin 



* 1 lu! pseudophite of Mount Zdinr, iu Moniviii, which contains onstatite antl which ditferi 

 from i^orpeutine hy tho presence of alumina, dues not yield veiy distinct crystals. 



t Do l.liaipetitier, Esuais sur la cimslil ulion gfiti^nuslujUR dts Pyriiiltis. 



X I'ournet, BulUlin Sue. (ieolufiujut dt t'rance, 2d series, t. iv, p. '2<17. 



$ 'I'schermak, BulUtin Acad, dis Scicncfs dc yienne, loc. citato. 



il III the WW repository of Iherzolite discovered by M. F. Saiidberpcr, in Nassau, that dis 

 tinjTUisliei-l geologist has observed all sorts of transitions of this peridotic rock into serpentine. 

 Lrdiiliarrt's .lalirbuck, I8G5, p. 441). 



lUSji ntbetic experiments on iiictamorpliism. (Annnles drs Mines, r>th series, t. xvi, p.4?-5.) 

 On the forniatiou o^ zeolites, {BulUlin i>uc. (Jeulogique de I'rancc, 'ZH series, t. xvi, p. 5bd ) 



