4-t2 Wright and Lav sen — Quartz as a Geologic Thermometer . 



No. 16 appear to have formed below that temperature, thus 

 indicating a temperature of formation of the large part of 

 the pegmatite at about 55()°-600°. Spec. 701. (E. S. Bastin, 

 collector.) 



26. Quartz from graphic pegmatite. Ilmen Mts., Miask District, 

 Urals, Russia. Coarse pegmatite consisting essentially of 

 microcline and quartz in characteristic graphic intergrowth. 

 (U. S. Nat. Museum.) 



27. Quartz from ore-bearing pegmatite vein in sodalite-syenite. 

 Bancroft, Ontario, Canada. Quartz is associated with 

 siderite, arsenopyrite and various sulphides. (A. C. Spencer, 

 collector.) 



28. Quartz from irregular pegmatitic mass adjacent to magnetite 

 ore, in Precambrian gneiss. O'Neil Mine, Monroe County, 

 N. Y. Dark colored rock, coarse-grained and consisting essen- 

 tially of abundant hornblende, microperthite and quartz with 

 some biotite and secondary chlorite. (A. C. Spencer, col- 

 lector.) 



29. Quartz from coarse pegmatite mass near magnetite ore body. 

 Stirling Mine, Lakeville, N. Y. Specimen consists of magne- 

 tite, hornblende (uralite?), biotite, quartz feldspar and some 

 secondary chlorite. Quartz occurs in small patches and 

 granules, scattered throughout .specimen. (A. C. Spencer, 

 collector.) 



30. White quartz from pegmatite in gneiss. Great Barrington, 

 Mass. Specimen consists chiefly of quartz with occasional 

 prisms of brown transparent tourmaline. (A. C. Spencer, 

 collector.) 



31. Quartz from pegmatitic mass in gneiss on John Keleyl's 

 farm, northwest end of Mt. Eve, Orange County, N. Y. 

 Specimen consists chiefly of magnetite, quartz and some 

 feldspar. (A. C. Spencer, collector.) 



32. Quartz from granite. Near Lake Bennett, B. C, Canada. 

 Medium-grained pink biotite granite. Spec. 314. (F. E. 

 Wright, collector.) 



33. Quartz from granite gneiss one-half mile north of Carpenter 

 Knob, Cleveland County, N. C. Gneiss consisting of feld- 

 spar, quartz, biotite and muscovite. (Arthur Keith, collector.) 



34. Quartz from altered granite, near Cambourne, Cornwall, 

 England. Specimen taken near tin ore deposits and consist- 

 ing essentially of pink feldspar quartz and black tourmaline. 

 (F. E. Wright, collector.) 



35. Quartz from altered granite near Cambourne, Cornwall, 

 England. Specimen from near tin ore deposits and intensely 

 altered. Much quartz and gray green altered feldspar, 

 muscovite and tourmaline. (F. E. Wright, collector.) 



36. Quartz from granodiorite. Near Log Cabin, White Pass, 

 B. C, Canada. Essential components of specimen are quartz, 

 oligoclase, orthoclase, and biotite. Gray medium-grained 

 intrusive. Spec. 303. (F. E. Wright, collector.) 



