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People Behind the Science

Victor Moritz Goldschmidt (1888–1947)

ictor Goldschmidt was a Swiss-born by the balancing of charge by means of sub-
VNorwegian chemist who has been stitution based primarily on size. This led to
called the founder of modern geochemistry. the relationships between close-packing of
Goldschmidt’s doctoral thesis on con- identical spheres and the various inter sti tial
tact metamorphism in rocks is recognized sites available for the formation of crystal
as a fundamental work in geochemistry. It lattices. He also established the relation of
set the scene for a huge program of research hardness to interionic distances.
on the elements, their origins, and their At Göttingen (1929), Goldschmidt
relationships, which was to occupy him for pur sued his general researches and ex-
the next 30 years. He broke new ground tended them to include meteorites, pio-
when he applied the concepts of Josiah neering spectrographic methods for the
Gibbs’s phase rule to the colossal chemi- rapid determination of small amounts of
cal processes of geological time, which he elements. Exhaustive analysis of results
considered to be interpretable in terms of from geochemistry, astrophysics, and nu-
the laws of chemical equilibrium. The evi- clear physics led to his work on the cosmic
dence of geological change over millions of abundance of the elements and the impor-
years represents a series of chemical pro- tant links between isotopic stability and
cesses on a scarcely imaginable scale, and abundance. Studies of terrestrial abundance
even an imperceptibly slow reaction can reveal about eight predominant elements.
yield megatons of product over the time Recalculation of atom and volume per-
scale involved. Lawrence Bragg after Max von Laue’s origi- centages led to the remarkable notion that
A shortage of materials during World nal discovery in 1912, could hardly have Earth’s crust is composed largely of oxygen
War I led Goldschmidt to speculate further been more opportune. Goldschmidt was anions (90 percent of the volume), with sili-
on the distribution of elements in Earth’s able to show that, given an electrical bal- con and the common metals filling up the
crust. In the next few years, he and his co- ance between positive and negative ions, the rest of the space. Goldschmidt was a bril-
workers studied 200 compounds of 75 ele- most important factor in crystal structure is liant scientist with the rare ability to arrive
ments and produced the first tables of ionic ionic size. He suggested furthermore that at broad generalizations that draw together
and atomic radii. The new science of X-ray complex natural minerals, such as horn- many apparently unconnected pieces of in-
crystallography, developed by William and blende Ca 2 Mg 5 Si 8 O 22 (OH) 2 , can be explained formation.

Source: From the Hutchinson Dictionary of Scientific Biography. © Research Machines plc 2003. All Rights Reserved. Helicon Publishing is a division of Research Machines.

Gneiss can also be produced by strong metamorphism of other
rock types such as granite. Slate, schist, and gneiss are but three
examples of a continuous transition that can take place from the
metamorphism of shale all the way until it is completely melted
to become an igneous rock.
Some metamorphic rocks are nonfoliated because they
consist mainly of one mineral, and the grains are not aligned
into sheets. When a quartz-rich sandstone is metamorphosed,
the new rock has recrystallized, tightly locking grains. The
resulting metamorphic rock is the tough, hard rock called
quartzite. Marble is another nonfoliated metamorphic rock that
forms from recrystallized limestone (Figure 17.21).

17.5 THE ROCK CYCLE
Earth is a dynamic planet with a constantly changing surface
and interior. As you will see in the next chapters, internal
FIGURE 17.21 This is a sample of marble, a coarse-grained
metamorphic rock with interlocking calcite crystals. The calcite changes alter Earth’s surface by moving the continents and, for
crystals were recrystallized from limestone during metamorphism. example, building mountains that are eventually worn away

448 CHAPTER 17 Rocks and Minerals 17-16