X-RAY MICROSCOPY 



7. Pattee, H. H., Jr., Garron, L. K., McEwen, 



W. K., AND Feeney, M. L., "Stereomicro- 

 radiography of the limbal region of the 

 human eye," in "X-ray Microscopy and 

 Microradiography," Academic Press Inc., 

 N. Y., 1957, pp. 534-538, Cos.slett, V. E., 

 Engstrom, A., and Pattee, H. H., Jr., Eds. 



8. Cohan, B. E., "Radiography of Aqueous Hu- 



mor Outflow," A.M.A. Arch. Ophth., 60, llO- 

 115 (1958). 



9. Cohan, B. E., "Aqueous humor outflow: An 



experimental study using opaque materials," 

 A.M.A. Arch. Ophth., 55, 793-799 (1956). 



W. K. McEwEN 

 M. L. Feeney 

 L. K. Garron 



GEOLOGICAL, MINERALOGICAL AND 

 CERAMIC APPLICATIONS OF 

 MICRORADIOGRAPHY 



Some of the first microradiographs ever 

 obtained were probablj^ of fossils and min- 

 erals (1) but such applications do not appear 

 to have been very common. However, an 

 interest is developing in uses of microradiog- 

 raphy for the examination of industrial min- 

 erals, concentrated ores and related mate- 

 rials such as refractories and ceramics. 

 Thus, applications to ores have been de- 

 scribed by Kirchberg and MoUer (2) and to 

 mineral concentrates by Cohen and Schloegl 

 (3). Other examples on ores by Jackson (4) 

 and Niskanen (5) have been published and 

 considerable work (6, 7, 8, 9) has been done 

 on sintered iron ores. In the field of refrac- 

 tories the work of Cockbain and Johnson 

 (10) indicates further potentialities for the 

 method. 



A technique for microradiography by re- 

 flection has been suggested by Trillat (11) 

 and by Pospisil (12) where secondary emis- 

 sion of electrons or x-ray fluorescence is re- 

 sponsible for producing the image. This 

 method appears to have no advantages over 

 the more usual technique using transmission 

 apart from the obvious one of not having to 

 make a thin section. This can be quite diffi- 



cult for some of the specimens considered in 

 this section. 



Figs. 1 and 2 show the differences between 

 the optical and x-ray transmission of a thin 

 section of iron ore. The ground mass of 

 siderite (iron carbonate) containing (juartz 

 inclusions shows up much more clearly on 



Fig. 1. Section of Jurassic Ironstone showing 

 ooliths surrounding angular quartz grains. The 

 matrix contains some quartz grains embedded in 

 siderite. Thin section photomicrograph — ordinary 

 light. X27. 



Fig. 2. Microradiograph of the same area as 

 Fig. 1 which now clearly shows the variation of 

 iron content in the concentric layers of the ooliths. 

 The angular shape of the quartz grains is much 

 more precise than in the photomicrograph. X27 



574 



