The record in the meteorites—IV origin of diamonds in iron meteorites

It seems t,o be the case that some laboratories arc not entirely sntisfiod that the avaifat)lt~ samples of G-1 and UT-l are aLtsoluteI~y homogeneous aa regards the content, of some tract elements present in minute amounts (e.g. fractions of a part per million), and this tends songwhat to reduce the usefulness of the samples. The powders supplied --l)artiunlarly (%--a~~ (~1 the coarse side, so that a sample weighing, say, 10-100 mg removed for analysis may not ,I’ its representative of the contents of the bottle ax would a sample weighing L gram. lf, on the ot h~:r hand, a larger sample is removed from the bottle and further mixed and ground boforc ~&SC. contLtmination is easily introduced, especittlly at t,he fractional part, per luillion le\,el. More investigat.ions of the traae element variation from bottle to botjtle of the samples should probably be carried out. In tjht: case of Pb in G-1, however (Part, 6 of the Bulletin, pp. 113--121, by E’. J. FLANAGAN), such an invrst,igat>ion has proved the Yamples to be homogeneous as far as this element is concerned, the trllc’ ~~alut: being about, 50 p.p.m., whereas previous analyses hacl shown a curious bimodal distribution centred about 27 and about 50 p.p.m. FLANAf:AT‘S description of the ~xperinlen~,s plsnned to resolve the problem of the 1% content. of (i-1 pro\-itlcs an object lesson in such matters. To conclude, it is apparent, that rather better rock analyses are probably being made now than 10 years ago-even if only because G--l and W-l are being used to calibrate rapid methods and check conventional ones-- but the position is still far from comforting. What is much more satisfactory is the widespread cooperation among geochemists interested in trace elements in

providing good figures for the two standard rocks, which perhaps find their greatest usefulness in this field. But what happens when the samples are exhausted? 5:. A. VINCENT

The wecard

in the

l!&eaIV

MICHAELE. LIPSCHUTZ and EDWARDANDEM (Geochim. et Coemmhim. Acta $34, 83-105) manuscript was mailed to Professor WAHL on June 28th, 1960, who was Editor for Cosmoohemistry at that time. We are advised that due to serious illness he was unable to process the manuscript; and that it was not received by an active member of the Board of

THIS

Editors until September 13, which is the date of receipt recorded in the Journal. We are anxious to have the point of earlier submission estab~shed, since the fir& ~de~ndent evidence in support

of our ideas, the

discovery

of coesite, was reported

on July

2&h,

1960 (CEAO,

SHOEMAKERand MADSEN,Science X3$&220-2) and our paper was completed before we learned of this discovery. Enrico

Fernai

In&&defor

Dqament of Clmn~try, Chicago, Illinois

N&ear Studies and University of Chicago

314

M~O~AIBLE. LIPSCHUTZ ED WARD ANDERS