1238 
Geology. — “Leucite-rocks of the Ringgit (East-Java) and their con- 
tact-metamorphosis’. By H. A. Brouwer. (Communicated by 
Prof. MOLENGRAAFF). 
(Communicated in the meeting of December 28, 1913). 
The following pages will afford new proofs of the intermediary 
place which the contact-metamorphosis of the basic leucite-rocks 
occupies between that of the trachytic and the basaltic rock. 
The Gunnong Ringgit (a corruption of the Madurese word reng- 
gik=saw-shaped) forms a steep mountain-range with five pointed 
tops on the northeoast of Java between Besuki and Panarukan; 
according to VERBEEK ') the whole mountain-range with the old crater- 
wall of the Gunong Besar south of it consists of lava-cakes and 
loose blocks of leucite-rocks. During a trip to Madura I visited the 
north-foot of the Ringgit; along the great postal-road at the north- 
foot lava is in several places found in situ. Near the 15 mi- 
lestone from Besuki, we see to the North of the road in the flat 
country one hillock consisting of leucite-lava forming a cape pro- 
jecting into the sea (marked I on the annexed map). The rock is 
a leucitite with phenocrysts of biotite which are much resorbed 
TFE Bt NE DU oor oA es 
RINGGIT 
1249 6 
to Besuki 
oe + 200 
whilst it is characterized by a great number of enclosures, measuring 
from a few centimeters to a few decimeters, and consisting, as far 
as they have been examined, of a reddish andesite. It is in these 
enclosures that the contact metamorphosis of the leucitites can be 
studied. 
IR. D. M. Verpeex en R. Fennema. Java en Madoera I. page 71. 
