238 JOSEPH P. IDDINGS AND EDWARD W. MORLEY 



at the cinder cone of the Bromo volcano in the old Tengger crater, 

 in Eastern Java, has been analyzed chemically with the result 

 shown in analysis No. 9, and proves to be a glassy variety of sho- 

 shonite, which shows no orthoclase, or other potassic mineral, in 

 thin section. The dull glassy matrix contains abundant large 

 phenocrysts of calcic plagioclase, having an index of refraction, jS, 

 which is 1 . 560, corresponding to labradorite, AbiAni.2, and much 

 fewer of brown vitreous augite. In thin section the groundmass 

 is seen to consist of brown glass full of prismoid plagioclase, equant 

 anhedral augite, and magnetite, with phenocrysts of labradorite 

 and a few of augite, oHvine, and magnetite. 



The recent basaltic lava of Goentoer volcano has been analyzed 

 also, and found to be hessose, with low potash, analysis No. 10. 

 The lava is dark gray, aphanitic, and porous; is minophysic with 

 few large phenocrysts of glassy feldspar with 18=1.575, which are 

 anorthite, AbiAuio, and many small ones of less calcic feldspar 

 and glassy yellow olivine. The groundmass contains a small 

 amount of globuHtic glass base, between abundant microHtes of 

 labradorite and fewer of augite, olivine, and magnetite. 



The Pic de Maros is a mountain of igneous rocks covered with 

 vegetation, which forms the southwestern extremity of a short 

 ridge, situated between Maros and Tjamba, north of Makassar, 

 in Celebes. Its rocks are exposed in place in a few localities, but 

 may be seen in great variety in bowlders in the stream Gentungen, 

 in the vicinity of Beleangin, and in loose material in drainage 

 channels at the north base of the mountain. From the last two 

 locaHties numerous specimens were collected by P. and F. Sarasin 

 and afterward were described by C. Schmidt. In a hurried visit 

 made by one of the authors of this paper some additional observa- 

 tions were made of rocks in place along the road on the west and 

 south flank of the mountain, and some other varieties of rock were 

 collected from the stream Gentungen. 



About 5 miles up the road from the rest house, Patinoean, toward 

 Tjamba there are large rounded exposures of massive shonkinite, 

 which is exposed again a mile farther on the same road, and at 

 other places. The rocks are dark colored, medium grained, and 

 are almost perfectly fresh on the rough weathered surface. The 



