OBJECTIONS TO LIQUATION HYPOTHESIS. 



127 



VN^ ^^^ v>s*> ^ VV V OsV't-v' 



occur as a result of primary diJEferentiation, then it would frequently characterize 

 intrusive masses, either with or without the presence of a gneissic structure. The 

 absence of observations in support of this is proof presumptive that it does not 

 exist. 



3. The relation of the ellipsoids and pyroxene bands to the inclosed apatite 

 crystals and masses. Their concentric arrangement about the apatite indicates 

 that the formation of the apatite antedated the development of the gneissic 

 structure. The difficulties in the way of considering that the formation of the 

 apatite deposits took place in the original magma are : 



a. Their large size. The deposits vary from a few inches in cross-section to 

 several feet, and often extend many feet in horizontal and vertical directions. The 

 crystals are frequently several inches in diameter. The larger crystals usually occur 

 in pockets in the pyroxenite, associated with pink calcite, mica, etcetera. A crys- 

 tal obtained at the Emerald mine, on the Du Lievre, and exhibited at the London 

 Exposition in 1886, measured 62J inches in circumference and weighed 550 pounds.* 

 Crystals one to two inches in diameter frequently occur in the granular deposits. 

 In pit number 11 at High Rock, a 

 crystal five or six inches in diameter 

 was observed in an inaccessible part 

 of the wall imbedded in the ellip- 

 soidal rock. 



b. Their inclusions. Doctor Hunt 

 noted rounded crystals of quartz and 

 carbonate of lime as inclusions in the 

 apatite, t Similar observations were 

 made by Emmons, J while Harrington 

 states! that the apatite crystals fre- 

 quently inclose calcite, pyroxene, 

 phlogopite, zircon, sphene, fluorspar 

 and pyrite. While it cannot be posi- 

 tively asserted that these inclusions 

 characterize the crystals imbedded in 

 the ellipsoidal rock, the correspond- 

 ence between these crystals and the 

 other deposits as to their occurrence 

 favors the supposition that they had 

 a similar origin. 



c. The rounded outlines of the apatite crystals. This feature of the apatite crys- 

 tals of the Laurentian veinstones was regarded by Emmons || as due to partial fusion, 

 while Huntf considered them to be the result of the solvent action of the heated 

 watery solutions from ^hich they were supposed to have been deposited. The 

 appearance of rounded angles on crystals found in cavities in the pyroxenite seems 

 to favor the latter view. 



liSsP^roxenite 



Figure 9. — Pocket in the Pyroxenite filled with Apa- 

 tite and Calcite. (After Harrington.) 



A large crystal of apatite projects from the side 

 of the cavitv. 



* Descriptive Catalogue of the Economic Minerals of Canada, London, 1886. 



t T. J. Hunt : Geology of Canada, 1866, p. 203. 



X E. Emmons: Geology of the First District of New York, p. 57. 



g B. J. Harrington : Geol. Survey of Canada, 1877-78, report G, p. 15. 



II E. Emmons : Geology of the First District of New York, pp. 57, 58. 



^T. J. Hunt : Chemical and Geological Essays (1891), p. 213. 



XVIII— Bull. Geol. Soc. Am., Vol. 7, 1895. 



