l8 NEW YORK STATE MUSEUM 



As to the external form of the serpentine, it is that of diopside 

 grains, when it simply replaces the latter, and these are commoinlT 

 roimded or irregular. In cracks, the serpentine, of course, conforms 

 to the opening and. thus, appears in straight or STnnous Tems or as a 

 network of these. As a replacement of calcite, serpentiiie some- 

 times develops along the cleavage of the latter { plate 2, figures i and 

 2) but. more commonly, is bounded by a series of intersecting 

 curves which may. however, be ven.- jagged in detail (plate 3, figures 

 I and 2). When present in small amount, it occurs in isolated 

 globular, reniform or irregularly rounded masses ([^ate 4, figure i), 

 sometimes connected by veins ( plate 4, figure 2) and as these spread 

 and coalesce, it increases up to a point when there is merely a little 

 calcite filling the interstices between adjacent masses of serpentine 

 (plate 5, figures i and 2). More rarely, serpentine dearly rq>laces 

 minerals other than calcite as, for instance, barite (plate 6, -figure i). 



Between the two t>"pes of serpentine, no sharp line can be drawn, 

 and there is no reason why a mass of serpentine resultrng from the 

 alteration of diopside in place, should not grow larger by the addition 

 of more serpentine from circulating solutions. As a matter of fact, 

 in many cases, grains of pseudomorphous serpentine haTe been 

 enlarged by the addition of rep.acerjient serpentine which, with its 

 characteristic 5::.' tttI : r es outside the anoothlj cnnred 



margin of the : t ^rain. Examples of this rdation 



are sh :t : - ^ rt z \ : ate 7. figure i. The ilhistraticHis 



i\ :\\: --.\y- :/ : :.t : — ; / : _ ' 7- tt/. 'r -' y-pes of sa^ 

 : r; : r : r : the contact 



between _ sei: : _ : ; / ■ t :::.\r ::. : ;._:_v. :tr as contrasted 



i.-— i-ilt. however, save m t^/pical cases. "/.y_/. " /t -/- r: 

 radier than the rule. 



Talc is much less a: V- ^ :.:- : :/-7 :-.^^ 

 pentine and. being easily confused with white mica, is n; t 

 to identify. Like sent ' - - " -- in n-vo forms — 

 tufts in calcite and 3.S - : ihe anhydrous i. 



the former, it has evidentl}" ' r t r:osited from circulating ~ 

 and has replaced an e r 



the original silicate, cr _ -: 



broke down in a manner closely ; 

 formation of serpentine. So far as 

 the latter mineral is formed ver\- lars'e'. 



