1893. ] - NEW YORK ACADEMY OF SCIENCES. 73 
strayed thither. But the past summer, in connection with the 
summer-school work of our Geological Department, two of our 
students, Messrs, Ries and ,Fennor, went, under the writer's 
direction, to the quarry, and prospected the neighborhood for 
norite. They were successful, and found the outcrop in the 
midst of the Archean crystallines. 
The general geological relations are well shown on the larger 
map by C. E. Hall (Sheet II. of Report C6, Penn. Geol. Surv.), 
and on this the accompanying small map has been based. The 
entire area was, however, covered by Ries and Fennor, and on 
their collections the rock determinations are based, As is shown 
on the large map the Archean rocks just touch the southwest 
corner of Bucks County, covering a township or two. They are 
of both massive and gneissic habit, and are collectively summar- 
ized by Hall as granitic and syenitic rocks. Ries and Fennor col- 
lected some green schist or amphibolite in square F2 of the small 
map. The general outcrop of this Archzean exposure forms an east 
and west belt, that at the quarry is about two miles across. 
The limestone outcrop is found in it at E2 and E3. It has 
always been a puzzle, because, as stated in Report C6, p. 59, it 
is the only exposure of limestone that occurs in this Archean 
belt. South of the Archzan belt lies the Potsdam quartzite, 
which, after a short distance, is succeeded by the Manayunk 
schists. North of the granitic belt there is the Triassic sand- 
stone with a conglomeratie streak along the contact. 
Van Artsdalen’s quarry is one of the best known and most 
prolific of the mineral localities near Philadelphia, and it 
frequently appears in the lists which have been prepared. In 
Genth’s Report on the Mineralogy of Pennsylvania (Report B 
of the Geol. Survey) the following species are recorded, the 
number of the page being given after each: molybdenite, 
p- 10; pyrrhotite, p. 17; pyrite, p. 20; blue quartz, p. 58; 
wollastonite, p. 64; pyroxene, p. 65; garnet, p. 74; zircon, 
p. 76; phlogopite, p. 82 ; muscovite, p. 85; wernerite, p. 86; 
feldspar, p. 89; orthoclase, p. 94; titanite, p. 103 ; apatite, 
p- 109 ; gypsum, p. 148. In Report BB, p. 225, an analysis of 
orthoclase is recorded. T. D. Rand, in his Notes on the Feld- 
spars, ete., of Philadelphia and Vicinity (Proc. Phila. Acad, 
Nat. Sci., 1872), mentions orthoclase, and J. Eyerman in his 
-Mineralogy of Pennsylvania, p. 22, refers to the same material. 
It has special interest on account of its chatoyant lustre. The 
notes on the mineral localities near Philadelphia, by Messrs. 
Rand, Jefferis, and Cardoza, in the Proc. of the Phila. Acad., 
1892, p. 182, give another list which mentions in addition to 
those above quoted from Genth, salite, fassaite, and coccolite. 
