346 Mr. William Phillips on the OxydofTin, 



neglect them in early life, which I have now occasion to regret, 

 not only as it forbids the pursuit of mineralogy to an extent which 

 alone would have enabled me to illustrate its objects in a manner 

 wholly pleasing and satisfactory, but also as it renders me incom- 

 petent to reap the pleasure and instruction, which the works of those 

 celebrated men the Abbe Haiiy and the Count de Bournon, are 

 calculated to convey. It must of course follow, that the only evidence 

 I can offer in regard to the admeasurement and value of the angles 

 of crystals, must be wholly mechanical. 



I have given much attention in the endeavour to ascertain pre- 

 cisely the value of the angles of this substance, by the help of that 

 admirable instrument the reflecting goniometer of Dr. Wollaston, 

 having been previously assisted in its use by some hints and per- 



conceive to be calcedony of a still lighter blue, though where most free from those veins, 

 the general colour and appearance considerably resemble; the chlorophane already de- 

 scribed. It seems to have formed the principal part of a vein, being accompanied on 

 each side by decomposing fluor, which has an ochreous crust similar to the gossan of 

 the mines. On being placed on a live coal it gives a green light, nearly as splendid as 

 the chlorophane, and does not fly ; but flies when placed in the fire. It scratches glass 

 easily. 



Another kind of fluor also encloses tin, which is of a light but dull brown colour, and 

 greasy lustre, and is somewhat transparent at the edges. Its fracture is shattery. It 

 gives nearly the same light as the chlorophane, but flies in the fire, though not when 

 placed on a live coal. One specimen, about an inch in thickness, has on one side, a 

 smaller vein of fluor, enclosed between two minute veins of chlorite, and on the other 

 side, compact white fluor; attached to each side, is a blue schist, the country of the 

 mine. From the numerous crystals of tin imbedded in some specimens, I am induced to 

 believe that it ran beside tin in the vein. 



I found also several other singular varieties of fluor, much harder and more compact 

 than fluor generally is, of which the fracture is shattery and the colour purplish. When 

 placed on a live coal, some of them begin by giving a greenish light, which soon changes 

 to purplish, and afterwards ends in a dark purple. Others, give only a purplish 

 light, and these do not fly even in the fire. Others give only a light green when placed 

 on a coal, without flying, but fly Avhen placed in the fire. 



