88 



MARINE BOTTOM SAMPLES OF LAST CRUISE OF CARNEGIE 



radiolarian ooze. Twenty analyses of the silt and clay 

 grades and of fine parts of maximum particle size rang- 

 ing from 30 to 0.3 microns from the pipette analyses 

 are shown. 



Patterns Used for Comparison 



For comparison, powder diagrams were made of 

 certain substances which may occur in deep-sea sedi- 

 ments and the interplanar spacings of certain other sub- 

 stances which may also occur were taken from the lit- 

 erature or were obtained from data prepared by 

 Mr. W. H. Dore. The data for sixteen such substances 

 are represented in table 30. 



Part A of table 30 gives data for the interplanar 

 spacings of sodium chloride, quartz, hyalite, calcite, 

 aragonite, hydrous ferric oxide (bog iron ore), psilome- 

 lane, pyrolusite, and phillipsite. In general, only ob- 

 served values are listed, although the calculated values 

 and the Miller indices of the interplanar spacings are 

 given for quartz, calcite, and aragonite. In some of the 

 other substances listed these theoretical values are not 

 known with any degree of certainty. 



The measurements given for sodium chloride were 

 made with the instrument used in the present investiga- 

 tion, and thus serve as a check on the accuracy of the 

 method. 



For quartz, the measurements given by Nagel- 

 schmidt and made with copper radiation, together with 

 the calculated interplanar spacings and indices given by 

 him, are compared with measurements prepared by 

 Mr. Dore with molybdenum radiation. In general, the 

 agreement between the two sets of measurements, 

 both with regard to numerical values and intensities, is 

 good. 



The values given for hyalite were obtained by Mr. 

 Dore from samples of banded opal donated by Professor 

 N. L. Taliaferro. Two sets of measurements- -one on 

 undried material having a water content of 8.2 per cent, 

 refractive index of 1.444, and specific gravity of 2.028, 

 and the other on material dried for 150 hours at 160°, 

 having no water, a refractive index of 1.386, and a spe- 

 cific gravity of 1.860-^gave identical results. The pat- 

 tern is probably that of cristobalite, even though the 

 appearance of the substance indicates a low temperature 

 of formation. Dwyer and Mellor state that opals asso- 

 ciated with sedimentary rocks show only a broad band 

 corresponding with either alpha or beta cristobalite. 

 The crystals in sedimentary opal are said to be less 

 than 0.01 micron in diameter. These facts are of inter- 

 est in this Investigation because of the presence in 

 many of the bottom samples of the opaline skeletons of 

 siliceous organisms, namely diatoms, radiolaria, and 

 sponges. 



The measured and calculated values and the in- 

 dices given by Nagelschmldt for calcite are listed. Be- 

 sides these, measurements made by Mr. Dore and the 

 writer on known calcite and on shells of foraminifera 

 separated from the sand grades of sample 44 are re- 

 ported. The foraminifera give a pattern identical with 

 that of calcite except for the presence of one very weak 

 aragonite line and of the strongest line of sodium chlo- 

 ride. 



The pattern given for aragonite is that of a crystal 

 from Bilin, Czechoslovakia, which was identified opti- 

 cally as aragonite. For comparison, needles of CaCOs 



precipitated from sea water by Revelle and Fleming 

 (1934), which the writer had previously identified tenta- 

 tively by optical means as aragonite, as well as the very 

 small needles identified by Merwin from Vaughan's 

 sample 177 from the Bahamas (see Vaughan, 1924), 

 were studied and the results are also presented in table 

 30-A. The X-ray results confirm the optical determina- 

 tions, both the experimentally precipitated needles and 

 the fine material from the Bahaman sample giving arag- 

 onite patterns. 



It is believed that many deep-sea sediments, partic- 

 ularly certain Globigerina oozes, contain free hydrous 

 ferric oxide. Accordingly, a sample of limonitic iron 

 ore donated by Professor Adolf Pabst was studied, and 

 the measured interplanar spacings are given in table 

 30-A. Unfortunately the interplanar spacings shown in 

 the pattern of this substance coincide with those of other 

 minerals known to be present in deep-sea samples. 



The data given for psilomelane and pyrolusite are 

 taken from Smitheringale (1929), who also gives data for 

 manganite, hausmannite, braunite, bementite, and wad. 



Twinned crystals and aggregates of phillipsite were 

 separated from the fine sand grade of sample 44 by hand 

 picking and the use of heavy liquids. The X-ray pattern 

 obtained is presented in table 30-A, together with a pat- 

 tern given by a phillipsite crystal from Australia, iden- 

 tified goniometrically by Dr. Adolf Pabst. The virtual 

 identity of the patterns confirms Renard's optical and 

 chemical determinations of the zeolite in deep-sea clays 

 as phillipsite. 



The interplanar spacings given by various authors 

 for the platy minerals glauconite and muscovite, and 

 the clay minerals kaolinite, halloysite, montmorillonite, 

 and beidellite-nontronite, are presented in table 30-B. 

 The similarity in crystal structure and habit of these 

 minerals is reflected in the coincidences of many of 

 their interplanar spacings. The presence or absence of 

 only a few lines is diagnostic for any one of the minerals. 

 Gruner (1932, 1933) has discussed the crystal structure 

 of kaolinite; and Hoffman, Endell, and Wilm (1933) have 

 discussed that of montmorillonite. 



The data for glauconite are based on measurements 

 by Dr. E. M. Thorp. Three of the patterns given for 

 muscovite are taken from Nagelschmldt (one of these is 

 from the work of Noll, 1932); the remaining muscovite 

 pattern represents data prepared by Mr. Dore. 



Date for kaolinite, the hydrous aluminum silicate 

 containing little or no bases and in which the silica 

 sesquioxide ratio is 2 to 1, were obtained from Nagel- 

 schmidt, Gruner, Ross and Kerr (1931, 1934), and 

 Hendricks and Fry (1930). Four of the patterns for 

 halloysite, similar to kaolinite in chemical composi- 

 tion but containing more water, are taken from Nagel- 

 schmldt, one from Kelley, Dore, and Brown, one from 

 Hendricks and Fry, and one from Ross and Kerr. In 

 addition, the pattern of a soil colloid of halloysite type 

 given by Hendricks and Fry is presented. Four patterns, 

 two of which are from Nagelschmldt, one from Hendricks 

 and Fry, and one from Kerr (1932), are given for mont- 

 morillonite, the hydrous magnesium aluminum silicate 

 in which the silica sesquioxide ratio is about 4 to 1, to- 

 gether with that of a soil colloid stated by Hendricks and 

 Fry to be of montmorillonite type. For nontronite and 

 beidellite, the isomorphous hydrous iron alumina sili- 

 cates in which the silica sesquioxide ratio is about 3 to 

 1, data prepared by Mr. Dore are presented. In addi- 

 tion, several patterns are given for bentonites which 



