Redpath Museum

These numbers corroborate the evidence at hand, or rather, underfoot. The evidence lockers for which elements pair together hest can he found in the mineral exhibits lined up in glass cases at any natural history museum. My personal favorite is somewhat old-fashioned, hut classic the Redpath Museum at McGill University in Montreal. 

The Redpath Museum doesn t have the biggest or most expensive specimens, but it does have the best-organized and best-labeled ones, from the perspective of this chemist. In too many museums, the mineral is labeled with only name and place (and, if you re lucky, donor, which doesn t exactly convey useful science). Such labels don t tell you much beyond historical accidents and abstract nomenclature. 

But the Redpath Museum does it right by making room for one more line, which may at first also seem like a jumble, but wait—it actually is a code. (Unlike Dan Brown s museum codes, this one works.) It s the chemical formula for the mineral in question, describing which and how many elements are in each rock. 

Oxygen plus silicon makes a common chemical group called a silicate. Glass cases full of sihcates stretch the width of the Redpath Museum. Look in the back of the physical chemistry textbook, and you will see that the heat of formation of silicon oxide is one of the largest numbers from combining the Big Six. Physical chemistry predicts that sihcates are prominent. 

The Redpath Museum has a few meteorites, although you can easily miss them. They re just tiny black rocks, some speckled, a few of bulbous metal, but none is very colorful. Geology was a lot simpler 5 billion years ago. In his paper describing mineral evolution, Hazen says the earliest meteorites have only 60 different minerals, about 20 of these in grains too small to see. The planetary disk and intense solar radiation worked like a blender on high speed, smoothly mixing the elements into hard, dark chunks of rock, rich in Hazen s Big Six elements. The other 77 elements were occasional impurities smoothly dispersed throughout. 

Oxygen has a special place on the wall of the Redpath Museum because it has a special place on the periodic table. It is the most common element in the northeast corner of the table, and all elements in this corner pull most on electrons. As the most compact and abundant electron-loving element, it was the most reactive element in the early universe. We just saw how it reacted with silicon and aluminum, leaving nothing freellibere. 

BIFs formed at two distinct times most formed 2-3 biUion years ago, and some formed 600-800 million years ago (Figure 8.1). The first BIF peak fits with the biological invention of photosynthesis and oxygen-eating metabolism described in the previous chapter. On the chemistry graph on the wall of the Redpath Museum, an... 

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