186 Canadian Record of Science. 



inclusions amount to from 1 to 3 per cent of the volume 

 of the mineral and goes on to say : " Le nombre des 

 microlites contenus dans un volume determine* est sus- 

 ceptible d'etre appr^cie* avec plus de precision ; les re*- 

 sultats toutefois s'e'carteront beaucoup entre eux, suivaht 

 l'^chantillon qu'on aura choisi et le point dans lequel on 

 Paura examine. Dans le labradorite violet figure le nombre 

 de microlites s'eleve au minimum a 10,000 par millimetre 

 cube ; mais pour autres vari^te's jaunes et gris foncees le 

 calcul m'a donne un nombre au moins dix fois plus con- 

 siderable de sorte qu'il y avait ici, dans l'espace borne* d'un 

 centimetre cube plus de cent millions de petits cristaux 

 strangers." The larger rods are surrounded by a zone of 

 clear feldspar. Some inclusions are transparent and have 

 a reddish brown colour resembling hematite ; these appear 

 in small scales which often show a somewhat distorted 

 hexagonal outline. Objects which closely resemble the 

 above mentioned rods, are often seen when very highly 

 magnified to be cavities, partly filled up by the dark 

 material of the rods. These inclusions are pretty uniform- 

 ly scattered through the feldspar individuals, and not con- 

 fined to certain places, nor present more abundantly in 

 some places than in others as is the case with the gabbros 

 described by G. IT. Williams l or by Judd.* 2 Minute fluid 

 inclusions may often be observed arranged in rows ; in these 

 there appears now and then a moving bubble. In one or 

 two cases small cubes were perceived in them, and in one 

 case it was thought that a double bubble could be recog- 

 nized. In two or three localities the otherwise normal 

 foldspar contained but few of these inclusions and conse- 

 quently was almost white in colour. The nature and 

 origin of these dark inclusions, which occur so frequently 

 in the feldspar and other constituents of the gabbro, in the 

 most widely separated localities of the globe, have been 

 frequently discussed. 



1 G. H. Williams, Gabbro and associated Hornblende Rocks in the neighbor- 

 hood of Baltimore, aid. Bull, U. S. Geol. Survey 28, p. 21. 



2 Judd, On the Gabbros, Dolerites and Basalts of Tertiary age in Scotland and 

 Ireland, Q. J. G. S. 1886, p. 82. 



