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33 o
mass curve we natst assun® about 25 ppm of gexrouiium or an atomic abundance
of 51 instead of aoWschmidt»s 188 for this quantityo
There is considerable
reason to believe that the germanium, tin and lead values selected by Qoldschmidt
are all too high as will be evident when tin and lead are discussed*
A recent value of Sar^ell (1955) for arsenic of 2.2 ppm in chondritic
meteorites or an atomic abundance of UoO seems to be very reliableo
This is
an average of Jh chondritic meteoriteso
The Moddadc's (193U) values are much
too hlgho
Tteir value together with our values for selenium, bromine and
7U
rubidium -will not give a snooth curve for the odd mass elements. Oe
more abundant than the neighboring even mass nuclides whose masses are
divisible by fours All nuclides from 0 to mass 68 whose nasses are
divisible by four a3?e either more abundant than their neighbors or the
inflections of the curve indicate that they are preferredo
Is
It may be that
75
this iiregularlty appears in the odd mass curve at As c We use an abundance
of 3o2 instead of U.O and avoid the irregularity in ttiecurve.,
PiTison, Ahrens and Franck (1953) have recently determined strontiimi 1»
metecRPites by improved techniques and report an average of 11 ppmo
This element
is highly coneenta^ated at the earth's surface, 100 to U60 ppm having been
repoartedo
(See Rankama and Sahama (15>50) p. it53 for a summary of data.)
Strontium is increased in the earth's crust to a smaller degree than bsyrium
axid to a greater degree than calciumo
We lower the observed value of strontium
by a factor of 1,5B or 0«2 in the logarithm, and barium by Oo68 in order to
correct for the concentration effects
This gives 12,lfor the atomic abundance
of strontiumo
Oar calcium value is the unchanged meteoritic abundaneeo
The abundances of yttrium and the rare earths are ijifficult to estimateo
The concentrations of yttrium in acidic and basic rocks are much the same, and