348 



PROFESSOR HEDDLE ON 



On 1*3 grammes — 















Silica, '457 





from alumina, ...... "005 





•462 



P.C. 



= 35-538 



Alumina, . 



35-55 



Ferric Oxide, 













•18 



Ferrous Oxide, . 

 Manganous Oxide, 

 Lime, 











• . 



7-12 

 •307 

 . 1-108 



Magnesia, . 



Potash, 



Soda, 













3-538 



1-072 



•429 



Boracic Acid (loss), 

 Fluorine, . 













10-768 

 1-705 



Phosphoric Acid, 

 Water, 











• 



trace 

 2-955 



100-000 



Fibrolite, ^th Si. Anorthic. 



This species was first recognised as British by the writer, but there is reason to 

 believe that it was noticed by Sowerby, although he was ignorant of its true 

 nature. 



In speaking of the andalusite of Auchendoir, while stating that it does not merge 

 into felspar, he remarks : " The nearest approach to mixing insensibly is by fibres, 

 which in ours are, however, sufficiently distinct." He also remarks: "The gangue is 

 chiefly composed of a coarse granite intermixed with indurated asbestos." 



In the first, if not in the second of these observations, he must refer to fibrolite, 

 and had he laid due weight upon the fact that the fibres were " sufficiently distinct," 

 he would have seen that they must have been a material different from the andalusiti 1 

 which he was describing. 



The fibrolite of Clashnaree occurs in three different modes of arrangement. 

 First, as a corded or stalactitic-like coating to the other minerals, somewhat after the 

 manner in which galmei coats galena. Here it forms a kind of sheath which 

 envelopes labradorite, quartz, and andalusite alike. Second, it radiates in bundles 

 of fibres through the labradorite, and these fibres often unite into a mass which 

 resembles okenite. This variety is very tough. Third, it frequently is disposed with 

 its fibres in parallel arrangement to the crystals of the red andalusite ; and long 

 slender crystals of the red andalusite are often imbedded amongst the fibres ol 

 the fibrolite. 



As the fibrolite is white or colourless, and of adamantine lustre, it is easily diatin 

 guished, and there is nothing of the nature of a transition ; it is a case of the main 



