Geology Reference
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mineral physicists and allied ourselves with the nonhistorical sciences of chemistry and
physics. Had we bought into the subtle prejudice against mere geological “storytelling”?
This mind-set reflects mineralogy's origins in mining and chemistry, colored perhaps by
a subliminal belief that the fields of physics and chemistry are more rigorous than the cre-
ative, qualitative yarns of the geologists. (Earth scientists often wonder if that bias might
have anything to do with why there are Nobel Prizes in physics and chemistry but not in
geology.) Consequently, few mineralogists have thought about the astonishing changes in
Earth's near-surface mineralogy through time.
When I joined with seven colleagues to publish our article “Mineral Evolution” in 2008,
our objective was in large part to challenge this traditional perspective—to reframe miner-
alogy as a historical science. Our venture into the mineralogical history of Earth, as well
as that of other planets in our Solar System and beyond, posits that Earth's mineralogy has
evolved through a sequence of stages, each of which saw changes in the diversity and dis-
tribution of minerals. Hence the narrative arc of this topic, in which planets progress from
mineralogical simplicity to complexity, from only about a dozen minerals in the dust and
gas that made our Solar System to more than forty-five hundred known mineral species on
Earth today—two-thirds of which could not exist in a nonliving world.
It was a highly technical article, published in the specialty journal American Miner-
alogist, usually read only by hard-core professionals. But the international media quickly
pickedupthepropositionthatlifeandmineralscoevolved. The Economist and Der Spiegel,
Science and Nature, andahandful ofpopular science magazines all seized onoureducated
guesses about a planet's changing mineral diversity. The New Scientist even published a
clever cartoon showing four “stages” of mineral evolution, from a swimming crystal with
fins to an “evolved” crystal with a walking stick. What none of them acknowledged was
that these provocative guesses were all speculative. Is Mars really limited to five hundred
mineralspecies?Arenonlivingworldsreallyunlikelytoexceedfifteenhundredspecies?Is
it true that it took a living, oxygenated world to triple Earth's mineralogical diversity? We
had presented these statements as hypotheses; the quest to test them had yet to begin.
And who could have predicted that the most fruitful place to look would be the rocks of
the boring billion?
To put quantitative flesh on the bones of the mineral evolution hypothesis, one must exam-
ine individual groups of minerals. Fortunately the world boasts experts in many different
mineral groups. That's why I contacted Ed Grew, a research professor in Earth sciences
at the University of Maine. Ed is a wiry, intense scientist who has devoted his life to the
meticulous study of the minerals that incorporate beryllium and boron—rare elements that
occasionally concentrate in big, beautiful crystals. He knows all 108 officially approved
beryllium minerals like old friends. Each has a character; each plays a geological role. So
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