240 



JOSEPH P. IDDINGS AND EDWARD W. MORLEY 



section these two varieties of shonkinite show much mica and augite, 

 with considerable apatite and magnetite. The inclusions in the 

 poikihtic mica are augite and plagioclase. There are large poiki- 

 litic crystals of orthoclase, and many small crystals of all the con- 

 stituent minerals of the rock. The chemical composition of this 

 variety is shown in analysis No. 15, which is not very different from 

 No. 16. Owing to somewhat more calcic feldspar in the norm, 

 which also appears in the mode, the rock belongs in kentallenose, 

 III. 5. 3. 3; more exactly it is III. 5 (6). 3 (4). 3, so that it may be 

 called a biotite kentallenite rather than biotite shonkinite. 



Another rock in the Gentungen bears a striking resemblance to 

 the pseudoleucite shonkinite, or fergusite, from Montana, de- 

 scribed by Pirsson.^ It has a dark gray, very fine-grained matrix, 

 with abundant equant, whitish pseudoleucites, irregularly scattered 

 and in clusters, the individual spots being about 3 mm. in diameter; 

 a few, 6 mm. There are also some small poikilitic plates of 



TABLE II 



Chemical Analyses of Rocks from Celebes, Borneo, and Sumatra 





II 



12 



13 



14 



IS 



16 



17 



18 



19 



20 



SiO. 



AlA 



Fe^O, 



FeO 



MgO 



CaO 



Na,0 



KjO 



H,0+ .... 

 H,0- .... 



TiO^ 



ZrOa 



CO2 



58.79 



195s 



1.82 



1.43 

 0.74 



2-37 

 4.21 

 8.69 



I. OS 

 0.06 



O.S4 

 0.00 



58.61 



21 .62 



X.16 



0.79 

 0.16 

 I. 71 

 6.60 

 6.82 

 1.42 

 0.19 

 0.17 



O.OI 



56.31 



21.69 

 1.20 



0.97 

 0.54 



1.88 

 5.56 

 9.17 



1. 13 

 0.00 

 0.41 

 0.00 



46.08 

 20.40 

 2.12 

 327 

 6.30 

 8.48 

 2.07 

 6.72 

 1.70 

 0.06 



1.39 

 0.00 



45.26 

 15-70 

 2.44 

 6.16 

 8.28 

 11-95 

 1-73 

 3-42 

 1. 12 

 0.29 

 1.66 



O.OI 



43-98 

 12.28 



3-49 



7-70 



8.00 



II .19 



1-33 

 5-06 

 1. 61 

 0.12 

 2.24 

 0.00 



46.04 

 12.40 

 3-54 

 5-58 

 12.60 

 8.38 

 1.62 

 4-87 

 3-55 



2.20 



46.05 

 14.88 

 4.22 

 5-78 

 5-98 

 13-47 

 1. 41 

 2.56 

 3.01 

 0.52 



0-93 

 0.00 



61.91 



16.26 

 2.45 

 3-96 

 1. 81 



4-35 

 4.40 



3-04 

 0.18 



O.IO 



0.79 

 0.00 



53-75 

 17.06 

 4.18 

 5.50 

 4.07 

 7.72 

 2,33 

 1-37 

 0.50 



0-39 

 0.88 

 0.00 



PA 



CI 



F 



S 



CrA 



MnO 



BaO 



SrO 



O.II 



0. 12 

 0.03 

 0.02 

 0.00 

 0.40 

 0.08 

 0.12 



0.04 

 0.07 



O.OI 



Tr. 



0.00 

 0.40 



O.OI 



0.02 



0.13 

 0.28 

 0.03 

 0.17 

 0.00 

 0.16 

 0.05 

 0.04 



1. 19 

 c. 10 

 0.09 

 0.06 

 0.00 

 0.19 



O.II 



0.07 



0.90 

 0.25 

 0.08 

 0.05 

 0.00 

 0-34 



O.IO 



0.06 



1. 81 

 0.12 

 0-15 



O.IO 



0.00 



o-Si 

 0.16 

 0.12 



"Tr!" 



0.59 

 0.09 

 0.03 

 0.04 

 0.00 

 0.21 

 0.06 

 0.07 



0.40 

 0.13 

 0.04 

 0.05 

 0.00 

 0.20 

 0.02 

 0.06 



0.25 

 0. II 

 0.06 

 0.06 

 0.00 

 0.50 

 0.02 

 0.12 





100.13 



99.81 



99.72 



100.40 



99.80 



99-97 



100.78 



99.90 



100.15 



99.87 



» L. V. Pirsson, U.S. Geol. Survey, Bull. 237, 1905, p. 74. 



