ART. 2. 



PETROLOGY AT GOOSE CREEK — SHANNON. 



13 



Apatite is a common though not abundant accessory. It seldom 

 occurs m the earlier plagioclase and never in the pyroxene. One 

 crystal of biotite contained small sharp apatite crystals. The char- 

 acteristic position of the apatite is in the interstitial micropegmatite 

 where it forms long needle like prisms penetrating both quartz and 

 feldspar. 



Quartz is present in smaU amount with orthoclase, forming rare 

 patches of fresh sharp micropegmatite occupying smaU angular inter- 

 stices between the other minerals. 



Iron ore, probably titaniferous magnetite, occurs sporadicaUy as 

 large irregular skeletal patches devoid of symmetrv. Much of it ap- 

 pears to be a late introduction developed by metasomatic replace- 

 ment of the earlier constituents. The fine opaque black inclusions in 

 the pyroxene appear to be iron ore and probably formed by separa- 

 tion of some of the iron and titanium originally contained in the 

 pyroxene. 



A sample of the diabase from the central part of the quarry face 

 which, upon microscopic study, was found to be typical and unaltered 

 was analyzed in the Museum laboratory yielding the results of column 

 1 ot tne following table. In column 2 are given the ratios of this 

 analysis, and in the other columns there are quoted, for comparison 

 other analyses of Triassic diabases and basalts from localities in the 

 JNewark series. 



Analyses of Goose Creek normal diabase and other Triassic traps. 



Al A 



FeA. 

 FeO_ 

 MgO . 

 CaO_. 

 NaaO. 

 KaO.. 

 H^O.. 

 Ti02-. 

 P2O5-. 

 MnO. 



Total. 



51.56 



13.81 



.96 



11.32 



7. 40 



10. 08 



2.08 



.96 



48 

 16 

 19 



100. 00 



0.860 

 . 135 

 .006 

 . 157 

 . 185 

 . 180 

 .034 

 .011 



019 



001 

 003 



51.78 



14. 20 



3. 59 



8.25 



7. 64 



10.70 



2. 14 



.39 



. 63 



1.41 



. 14 



.43 



50.34 



15.23 



2.82 



11. 17 



5.81 



9. 61 



101. 30 



93 

 02 

 26 

 56 

 14 

 14 



1. 60 



101. 03 



.44 

 99. 76 



1. Analysis of average diabase, GoosT^CreekTvaTEyT^ha^i^^ir^^^ 



2. RaXs ori.^'""^^^ '' ''""'"' '" ^^*^^^--t-ns being direct ' ' 



186; Tsrt """'' ''"^"•' ""• ''- ^^"^^' ^"^^--*' •^--- J— Sci., vol. 9, p. 

 285; ?8'99.' """'' ""• '•' ^- ""■ ''^'"^P^' ^""^^^*' '^--- J--"- Sci., vol. 8, pp. 267- 

 186; mT ^"^^^^^'^^^--'G-W.Hawes, analyst, Amer. Journ. Sci., vol. 9, p. 



