250 THE CANADIAN NATURALIST. [Vol. ix. 



ther alteration of the rock into chlorite, and this finally into a 

 mixture of brown iron ore, quartz and carbonates. -'"^ " 



The above facts have been cited because of interest in connec- 

 tion with what now follows concerninii' the alteration of certain 

 pyroxenes in the apatite region of Quebec. The best examples 

 were observed at the mines of Mr. Breckon, on the twenty- third 

 lot of the thirteenth range of Templeton, where crystals have 

 been obtained showing perfectly the transition from pyroxene to 

 what may be called uralite. The crystals are mostly flattened 

 in the direction of the orthodia2onal, and while some of them are 

 apparently quite unaltered, others have been converted into horn- 

 blende for a greater or less depth from the surface ; others, again, 

 are entirely changed to hornblende, and show no trace of pyroxene 

 even when sliced and examined microscopically. In the first 

 stage of alteration the pyroxene, which in its original condition 

 is glassy and of a grey color, becomes more or less dull and green- 

 ish or greyish-white, still, however, retaining the cleavage of 

 pyroxene. In this pale portion acicular prisms of green horn- 

 blende begin to be developed, gradually increasing until in some 

 cases, all trace of pyroxene is obliterated. The change appears 

 to have always begun at the surftice of the crystals, extending 

 inwards more rapidly in some parts of the crystals than in others, 

 but although the hornblende prisms at the surface appear to be 

 mostly parallel Avith the principal axis, within they are seen to 

 run in every direction, or in some cases to be arranged in radiat- 

 ing groups. Intermingled with the hornblende prisms a little 

 calcite occurs in places. 



Even when the crystals have been entirely changed to horn- 

 blende the pyroxene angles remain perfectly^ distinct, and one 

 crystal with terminal planes shows the following combination ; 

 cc P oo. 00 P. [oo P O)]. P cc . - P. 2 P. The crystal is an inch 

 and seven-eighths wide and a little over half an inch thick. The 

 remaining portion of another crystal, which has lost its terminal 

 planes, is three inches wide and an inch thick, and apparently 

 wholly uralite. The crystal which supplied the material for the 

 following analyses was about an inch and three-quarters wide 

 and an inch thick. The centre consisted of glassy grey pyroxene, 

 surrounded, however, by the dull and pale material described 



* For otlier interesting details concerning uralite see Zirkel, Mik, 

 Beschaff^ d. J/in. u. Gest. p. 178. Also Rosenbuscli, Mik. Phijsiog. d. Min.. 

 p. 316. 



