190 W. E. Ford — Optical Study of the Amphiboles. 



Tremolites and Actinolites. 





I 



II 



III 



IV 



V 



VI 



VII 



VIII 



SiO s 



57-47 



57-69 



55 02 



56-25 



54-80 



55-21 



51-85 



54-52 



Ti0 2 





0-14 







o-io 





1-26 



0-39 



Al a O, 



1-28 



1-80 



4-53 



V-24 



2-58 



3~-45 



4-36 



9-25 



Fe a O a 



0-18 



. . _ 



1-04 



0-78 



2-50 





2-58 



4-44 



FeO 



0-22 



055 



3-28 



5-50 



475 



7~-49 



546 



9-81 



MnO 



007 



tr. 





0-48 



tr. 





35 



0-46 



MgO 



24-87 



24-12 



20-36 



21-19 



2030 



18-97 



19-48 



10-33 



CaO 



12-84 



13-19 



8-00 



12-08 



12-08 



10-50 



10-60 



1-98 



K 3 



0-49 



0-22 



1-52 



0-28 



0-24 





0-35 



0-16 



Na 2 



0-68 



0-48 



6-71 



0-19 



0-82 



2~-45 



2-15 



7-56 



H 2 



1-30 



1-56 



0-51 



1-81 



1-60 



1-75 



1-21 



1-78 



F 



0-77 



0-37 



---- 



0-04 



0-77 



---- 



0-46 









100-19 



100-22 



100-97 



99-84 



100-65 



99-82 



100-24 



100-68 



Total Fe 



0-29 



0-42 



3-27 



4-81 



5-44 



5-82 



6 24 



10-84 



Extinction 

 angle 



20T 



16°38' 



16°16' 



14°59' 



14°47' 



14°34' 



13°35' 



8° 



Mean index 



1-612 



1-618 







1-631 



1-629 



1-639 



1-641 







I. Eichville, see p. 181. II. Lee, see p. 181. III. Szechenyite, see 



Krenner, Zs. Kr., xxxi, 502, 1899. IV. Greiner, see p. 181. V. Russell, 

 see p. 181. VI. Berkeley, Blasdale, Bull. Univ. Calif., ii, 333, 1901. VII. 

 Kragero, see p. 181. VIII. Blasdale, Bull. Univ. Calif., ii, 338, 1901. 









Hornblendes 













IX 



X 



XI 



XII 



XIII 



XIV 



XV 



XVI 



SiOo 



43-76 



41-99 



43-35 



40-52 



45-20 



39-58 



42-74 



36-86 



Ti0 2 



0-78 



1-46 





1-71 



0-84 



tr. 



1-08 



1-04 



Alo0 3 



8-33 



11-62 



8 : ii 



10-99 



7-34 



14-91 



5-48 



12-10 



Fe 2 3 



6-90 



2-67 



7-91 



9-64 



755 



4-01 



11-92 



7-41 



FeO 



10-47 



14-32 



10-11 



9-83 



15-80 



10-67 



11-46 



23-35 



MnO 



0-50 



0-25 





tr. 



1-52 



tr. 



0-06 



0-77 



MgO 



1263 



11-17 



14-33 



11-82 



8-40 



13-06 



11-60 



1-90 



CaO 



9-84 



11-52 



13-21 



12-33 



12-30 



11-76 



12-72 



10-59 



K 2 



1-28 



0-98 



1-87 



0-68 



0-37 



62 



0-56 



3-20 



Na 2 



3-43 



2-49 



2-18 



2-38 



0-80 



2-87 



2-25 



1-20 



H 2 



0-65 



061 



0-91 



0-50 



0-70 



2-79 







1.30 



F 



1-82 



0-80 





.... 



.... 



100-27 



---- 



027 





100-49 



99-86 



100-98 



100-40 



100-82 



99-69 



99-99 



Total Fe 



12-98 



12-99 



13-38 



14-38 



17-35 



11-09 



17-24 



23-33 



Extinction 



















angle 



33°20' 



23°48' 



17°56' 



17° 



15° 9' 



15° 



14°40' 



9° 



Mean index 



1-67 



1-668 







1-6741 











1-67 



1-71 



IX. Renfrew, see p. 181. X. Edenville, see p. 181. XI. Artificial 

 amphibole, Chrustschoff, Jb. Min., ii, 86, 1891. XII. Soretite, Duparc 

 and Pearce, Bull. Soc. Min., xxvi, 126, 1903. XIII. Pbilipstadite, Daly, 

 Proc. Am. Acad. Sci., xxxiv, 433, 1899. XIV. Piedmont, Van Horn, Am. 

 Geol. xxi, 370, 1898. XV. Cbester, Duparc and Pearce. Bull. Soc. Min., 

 xxxi, 118, 1908. XVI. Cornwall, see p. 181. 



