47G Pr<f. T. (I. I'.oimey. On Bonlden and othtt lfa Specimen* 



(/'.) Another specimen, apparently alx-ut half >f a fairly well-worn 

 boulder, is not |iiite sn large, ("ndcr the mi-roscopc it is found t< IK- 



practically identical in composition, but a little mon- >c; pentinisrd ; a 

 clear i>otropi<- mineral sometimes forming a Imrder to the enstatite. 

 The presence of any original grains of iron oxide is douhtful, lut one 

 or two of augite can IK- recognised, Moth sjM-i-inieiis. however, may In- 

 named Saxonites. 



(''.) Not very much worn, and rather triangular in shajie. alioiit 

 :> indies by I inch, and about O'G inch thick, consisting apparently of 

 garnet, two pyroxenes and jK-rhaps olivine. Microscopic examination 

 shows olivine. almost wholly converted into serpentine, enstatite parti- 

 ally changed to another (the usual) variety of the same mineral ; 

 chrome diopside. a little colourless augite, with a diallagic hal>it. and 

 pyrope (two specimens). As the last-named mineral is not abundant, 

 the rock is more nearly related to the Lher/olites than to the Kuly>ites, 

 and so may lie named a granatiferous hher/olite. 



('/. ) A roundish Hat slali alioiit .'{"> x :.'"> x UMi inches, containing 

 red garnets, enstatite. and a bright green pyroxene. Micros.-opic 

 examination shows olivine. jKirtly convei'ted into a dull yellowish-green 

 serpentine, chrome diopside. -due enstatite. now altered to a serjHMi- 

 tine. the colour suggesting that it is ehromiferous, and pyrope (not 

 abundant). A little jwdc liniwn mica, probably secondary, occurs 

 about the garnets and the diopside, in one case occupying a crack. 

 The rock belongs to the granatiferous peridotites. and though it con- 

 tains less enstatite than the last one. may also IK; regarded as a variety 

 of Lherzolite. 



('-.) The next specimen is evidently a fragment, the angles and 

 edge- of which have lieen slightly worn, as if by water. It measures 

 aliout .'U by '{ inches, and 1] inch in thickness. The rock in the 

 freshev part consists of pyrope. and two minerals of a dull-green 

 colour, but about half of one surface is affected by decom{Misition. 

 which has penetrated to a depth of about | inch. Here one of the 

 pyroxenic minerals ap]>ears to IK? a pale-coloured bastite with the usual 

 metallic lustre : the other of a brighter green tint. Examination with 

 the microscope shows the following minerals: (1) Olivine in various 

 stages of conversion into serpentine; some grains l>cing traversed 

 as usual by very pale-green strings of the latter mineral, others 

 completely changed into it. and of a yellowish or brownish colour: 

 minute dark -brown needles are sometimes present ( ? rutile). (2) Bas- 

 tite with a well-developed pinacoidal cleavage: sometimes partially or 

 even wholly converted into a fibrous material, which with transmitted 

 light is a rather rich green colour, the usual small brown negative 

 crystals being develoj>ed in some grains. (3) A very pale sea-green 

 augite. probably a chrome diopside. (4) Pyrope : the grains having a 

 kelyphite rim and showing incipient mineral change along the cracks. 



