Friends are Electric

There are exactly five Nobel Prizes awarded every year, with one more masquerading as a true Nobel Prize. Our friend Alfred specifically set up three of these five prizes to reward scientific developments which have benefited human kind. In the case of the peace prize, an individual or individuals who have furthered the cause of world peace, and with literature, those who further the understanding of what it means to be human. Whether these awards have always reflected their original purpose is open to question. This is not the question for the moment, however.

There is another prize, one which ostensibly seems to be awarded for scientific achievement in a field of study. Of course, this field is as unscientific as the study of history, but few realise or are willing to accept that. I speak, of course, of that mighty social science, economics.

There is no doubt that the prizes in medicine, chemistry and physics are all rewarding true scientific achievement. But what makes these fields scientific and economics not? I would argue that it is the nature of what is being studied. Medicine, strictly, would not exist without purposeful human study, but the subject of their study, biological organisms, would. The same can be said about chemistry and physics, as prior to humans both played the same role they do now in the universe. Economics, however, is entirely different. It is emergent from human behaviours. It is not separate and independent from humanity. In short, it is not universal.

Economics is a social science. Social sciences are quite unfortunately named, since they have little if nothing to do with science. Which is not to belittle them, merely condemn them to a specific sort of operation, ideally closer to that of the humanities than the natural sciences. However, that is a discussion for another time. Being a social science, economics must understand that what it pretends to be is false, that it is not, as said above, universal and is, more importantly, not fundamental.

Not fundamental. No other social science, humanity or indeed natural science places itself on such a pillar of self-importance. Economics claims that only economics is the lense which we can judge our actions, plans and programs. Perhaps other fields would make such claims if they were in a position to, but certainly we would recognize the absurdity of judging everything through the principles of anthropology. It is not that anthropology has nothing important to tell us, quite the opposite really, it is that a single lens view of society is an impossibly terrible way of running things.

The reason why no other social sciences have Nobel Prizes? None of them have rich backing organizations. That is how this prize came about, a Swiss bank funded the prize, a Nobel Memorial Prize. I would argue that they did so to increase the credibility of the field as a science, rather than as just one of many social sciences which we attempt to understand our society with.

A final point on the relevance of a prize in economics: other fields attempt to describe laws of nature, but the way nature functions does not change based on these laws, not true for economics. For example, gravity works as gravity no matter how we describe it, be it Newtonian, Relativity or some future Quantum-Gravity theory. Economics does not behave this way, if a new mindset takes over, the way the system itself functions can change. This is because it is an emergent system which requires humans, or something similar, rather than fundamental to the nature of the universe.

In all of my time studying engineering and science, I have never come upon something as useful and nearly perfect as Bowen’s Reaction Series.

For those who have yet to be made aware of it, Bowen’s Reaction Series shows the relation between various minerals of igneous (molten rock) origin. There are three parts to Bowen’s Reaction Series, the continuous reaction series, the discontinuous reaction series and the residual phase. I’ll talk about each part in more detail and move on to a few interesting applications of Bowen’s Reaction Series in mineralogy.

The layout of Bowen’s Reaction Series is such that as you move up the series (towards olivine and calcium plagioclase), the melting temperature increases. Calcium plagioclase and olivine do not have the same melting temperatures but are usually placed at the same height for aesthetic reasons. This means that quartz, muscovite and potassium feldspar melt at the lowest temperatures.

Related to the melting temperature is thermodynamic stability. Minerals which crystallize at a high temperature tend to be stable at such temperatures, and are less stable at atmospheric conditions. Olivine, therefore, weathers very easily under standard conditions. This helps to explain why quartz is the leftover in beach sand. Quartz is resistant to chemical weathering and is commonly left behind. The mechanical weathering of waves may wash away other materials, but quartz will remain behind. Olivine and pyroxene, the two mineral types on the discontinuous series with the highest melting points, weather extremely easily and are thus unlikely to form such deposits.

Anyone not interested in a more detailed discussion of the chemistry of Bowen’s Reaction Series should skip ahead to the final section on interesting applications of Bowen’s Reaction Series.

The Discontinuous Series

The discontinuous series is the most interesting part of Bowen’s Reaction Series. It is here where the most interesting chemistry takes place. As mentioned already, olivine is the first mineral to crystallize out of a melt. Olivines have the general formula (Ca,Mg,Fe)(Mg,Fe)SiO4. Calcic olivines are metamorphic minerals and will not be discussed further. Magnesium rich olivine is known as Forsterite, and melts at a temperature much higher than the iron-rich end member, Fayalite.

If an olivine, (Ca,Mg,Fe)(Mg,Fe)SiO4, reacts with quartz, SiO2, it will form a pyroxene, (Ca,Mg,Fe)(Mg,Fe)Si2O3. Unlike olivine, calcium pyroxene (known as clinopyroxene) are found in igneous formations. Orthopyroxenes do not contain calcium. Ortho and clinopyroxenes have different crystallographic structures since calcium ions are enough larger than iron and magnesium to force a change in the structure.

Adding another SiO2 and water to a pyroxene will produce an amphibole, (Ca,Mg,Fe)2(Mg,Fe)5Si8O22(OH)2. Amphiboles are minerals that we begin to see more regularly in light coloured volcanic rocks, such as granites. Amphiboles show a lot more chemical variability than either pyroxenes or olivines. Sodium ions are capable of substituting for any of the (Ca,Mg,Fe) ions and minerals with up to three sodium ions exist. To maintain charge balance, however, if a sodium is substituted for one of these atoms, an aluminum (3+) must substitute for a silicon (4+). Al-O bonds are slightly weaker than Si-O bonds and thus only up to half of the silicon in a structure is available for substitution.

As all of the above minerals crystallize from the melt, thee melt becomes rich in potassium and silica (SiO2). The last mineral in the discontinuous series has plenty of silica in its structure and contains potassium, a very large ion. Biotite’s chemical formula is K(Mg, Fe)3AlSi3O10(OH)2. Like all other mineral classes on the discontinuous series, it has a high temperature magnesium and a low temperature iron end member.

Each mineral class in the discontinuous series has an increasing degree of polymerization than the last. Olivine is a nesosilicate, meaning that the silicon-oxygen tetrahedra (which comes from the relative size of the two ions) are physically isolated from each other and no polymerization has taken place. Pyroxenes are single chained inosilicates, meaning that they have a linear chain of tetrahedrea linked together. Amphiboles are also inosilicates, only two of these chains have joined to form a wider sheet. Lastly, biotite is a phylosilicate, meaning that many such chains have joined such that the resulting polymer structure is infinite (compared to the size of the atoms) in two directions, forming a sheet.

The Continuous Series

Unlike the discontinuous series, where earlier minerals react with the melt to form later minerals, once a mineral is formed it remains unless remelted. The continuous series features only one mineral, plageoclase feldspars, varying from calcium-rich (anorthite) to sodium-rich (albite) end-members. All feldspars are tectosilicates, meaning they are polymerized in all three directions forming a complex network of interconnected silica tetrahedra. The way these minerals form tend to produce a zoning effect, where within a crystal calcium content decreases as you move from the centre to the edge.

As you move from albite to anorthite, an increasing number of silicon atoms must be replaced with aluminum atoms to ensure charge balance.

The Residual Phase

The residual phase is whatever is left over after both reaction series have run to completion. As it cools, orthoclase (potassium) feldspar forms, as well as muscovite mica and quartz. Quartz and orthoclase are both tectosilicates (3D network), while muscovite is a phylosilicate (sheet).

Interesting Uses

Now that I’ve walked you through the basic chemistry, its time to examine a few reasons why Bowen’s Reaction Series is such an amazing tool, aside from chemical and temperature relationships and weathering.

The first is something I’ve already referenced, as you move down the series, crystal structures generally become more complex. From olivine with no polymerization to quartz with perfect three dimensional polymerization, all in one easy to see chart. I say generally since it is common to group all of the feldspars together (as above), which separates biotite and muscovite mica.

Crystal structure determines many physical properties. For example, micas break off into thin, flexible sheets because all of the silica tetrahedrons point in the same direction, all of the upward facing oxygen are coordinated (bonded) to potassium, which is so large that it needs 12 oxygen to bond to. This means that the potassium-oxygen bond is extremely weak (1/12 of the silicon-oxygen bond). Since the structure forces these to form linear sheets, its no wonder micas cleave the way they do.

The third thing is incompatibility. You will never find an olivine and a quartz in the same rock. Why? If there was silica in the melt, it would have reacted with the olivine to form pyroxene, leaving either less olivine and no silica or no olivine and less silica.

Finally, Bowen’s Reaction Series allows us to explain what we see in rocks. We know that a granite, rich in quartz, feldspar and biotite, is the result of a relatively iron-magnesium free magma which crystallized at lower temperatures. A dunite, on the other hand, is mostly olivine and so had to crystallize at high temperatures and become physically separated from the rest of the melt and its silica. Combine this information with the size of crystals observed in the rock, which determine the rate of cooling, and even an amateur like myself can tell a rock’s story with ease and accuracy.

That is why I find Bowen’s Reaction Series to be so fascinating, with only two other pieces of information (bonding rules and crystal size in relation to cooling rate) you can explain most common minerals and the rocks they make up. It is a very powerful tool in earth history and mineralogy.

A thought has been worrying me a lot recently.

I am a man of reason. To me, there is nothing more fundamental. I follow my reasoning wherever it takes me. Since I am an engineering student, this is a rational way to be. Science follows reason. It is natural.

What is strange to me is how we, as a society, become convinced of unreasonable things. I speak now of creationism. Not that some subscribe to this belief, I can understand that. I do not wish to prevent others from believing what they wish. What is in one’s own mind is no business of mine. What I mean is about the conflict between creationism and evolution.

I say conflict, but this is somewhat misleading. Reason dictates that evolution is truth. Let us not get bogged down in any details. Anyone needing convincing of this fact is invited to educate themselves. Biological evolution is a fact. This, then, is at the root of what is confusing me.

Evolution is truth in terms of the origins of life. Darwin was wrong in the same sense that Newton was wrong. Science progresses. Evolution is correct, just as gravity is correct, albeit both have been and will be modified in the future as that is the way of science.

My question is this: If evolution is so clearly true, which it is, how has society been convinced that there is even a `debate’ between creation and evolution. This is the true triumph of creationists, since creationism is provably false. But convincing the masses that there is descent is an impressive feat, one which deserves recognition and retaliation.

I do not call for violence.

I do call for reason.

Whenever you hear someone speak of a debate between creationism and evolution, set them straight. Science knows the truth.