1889.] Mineralogy atid Petrography. 811 
of Devonian. Between the two are as ot older rocks a tract of great 
extent, in the centre of the island, is occupied by coal-bearing strata. 
The lower series of these contains plants of Carboniferous age, but the 
higher coal-measures yield many plants of Mesozoic affinities. These 
strata have been invaded by igneous intrusions, and are to a great ex- 
tent covered by Tertiary beds. 
MINERALOGY AND PETROGRAPHY.' 
Petrographical News. — A new type of rock has been discovered 
by Mr. Arnold Hague^ in the Absaroka Range, Wyoming Territory. 
It was found as a boulder in the gorge of the Ishawooa River. The 
most striking feature of the rock is the nimiber and size of the grains 
of fresh olivine scattered through it, the only other macroscopical 
ingredient being augite. These two minerals lie in a ground-mass 
composed, principally of leucite smd orthoclase, together with a small 
amount of plagioclase, magnetite, apatite, and minute flakes of brown 
mica. The rock is particularly interesting as the third occurrence of 
a leucite rock in North America. The leucite is partly idiomorphic 
and partly allotriomorphic. Some of its crystals are isotropic, while 
others show optical anomalies. A number contain minute augite 
grains as inclusions, arranged centrally or in a spherical zone about 
the centre of the crystal. An analysis of the rock reveals a very low 
percentage of potassium, a percentage so low as to suggest the exist- 
ence of such conditions during the solidification of the rock as to 
allow of crystallization in two very distinct stages. The analysis was 
made by Mr. Whitfield. 
SiO, TiO, Al^O, Fe,03 FeO MnO CaO MgO Na,0 K,0 CI P,Oj H,0 
47-28 .88 11.56 3.52 5.71 .13 9.20 13.17 2.73 2.17 18 -59 2.96 
Two new localities for camptonite have been reported from the New 
England States within the past summer. The first is near Whitehall, 
Washington Co., N. ¥., where Messrs. Kemp and Marsters> discovered 
dykes cutting the Georgia slates. In addition to the usual features of 
