Month: December 2012

On the brink of 2013

Around this time last year I was sitting in the bath, fully clothed, with my laptop on my knees.

I was hiding from a mouse that I’d spotted scampering across the living room having figured that he or she wouldn’t be able to climb past the overhang of the edge of the tub so I could rest easy and carry on my hitherto solitary celebrations.

The celebrations themselves consisted of DVDs — I can’t remember which so probably just a mixture of US television comedies — and the Sprite left over from my Happy Meal. I’m not entirely sure whether the fact I had “grown-upped” the Sprite with liberal glugs of some homemade sloe gin makes this tableau more or less depressing.

So yes. Sitting in a bathtub, wearing lots of outdoor clothes in case the mouse somehow tried to touch my bare skin, drinking gin out of a Happy Meal cup and completely unable to enjoy or remember Modern Family.

I considered sleeping in that tub.

I also didn’t go back into the living room until my boyfriend at the time came home except for a trip (clad in wellies, gloves and a hat) to poke a mousetrap stuffed with apple and peanut butter through the door with a broom.

I’m not even going to concede that this was damaging to gender stereotype advances because, you know what? ANYONE can be scared of a mouse.

The fact that I later discovered said mouse had died, frazzled against the power pack of the boyfriend’s computer and that the way I found this out was by mistaking the corpse for an old apple core and almost putting my hand through it… Well let’s just say that species has not endeared itself to me any further.

This year I am hoping for better things. I have a house party I am about to head to, I live with a flatmate who has a cat and therefore a wonderful lack of mice, and I have even more sloe gin than last year.

But the end of this year has been a strange one.

In an email to a friend I described returning to London to find it feeling far less like home than before I went to see my family for Christmas. Like the holidays grabbed at the chessboard and shook it around just as the shape of a game was forming. Rootlessness, perhaps? Realising that the pieces which you had mentally fixed in place because that’s how you have to play are actually no more attached to their actual squares than you are to your metaphorical one.

A slightly odd sensation, then, but one filled with potential and with the idea that you take your own potential moves with you wherever you go.

I’m not sure what the next year will hold and I don’t believe that change comes from a calendar tick but I think it’s best to say that perhaps I am a person in flux and the flux will be the curious thing about 2013.

The fascinating world of granite!

I started finding out about granite after reading that it was naturally radioactive. I hadn’t really given it much consideration before and suddenly felt very ignorant. Then I ended up staying awake until 5am reading more and more about it! For the information about radiation you can skip through to the end, but there was also plenty of other interesting stuff I found out so I’ve popped that in too.

**What on earth is granite?**

So let’s start with the absolute basics. Granite is an intrusive igneous rock – that just means it is formed below the surface of the earth as magma or lava cools. Because the cooling happens underground it takes a very long time and that allows the rock to form large crystals which are visible to the naked eye. That’s why granite can end up looking like a rocky fruit cake.

Granite is composed of between 20-60 percent quartz (silicon dioxide), lots of feldspar (a family of silicate minerals) and then a selection of other minerals which give it different darknesses and textures. To work out if something is a true granite or just a granitoid you need to know the relative proportions of quartz and feldspars. There’s even a helpful triangle to help with that – the bits in green are the true granites:

How it works is you find out the percentage quartz in the rock and plot that as a horizontal line, then you look at the feldspar content and work out the what percentage of that is plagioclase feldspar as opposed to alkali feldspar. That goes along the base of the triangle. Then you draw a line from that point on the base to the apex of the triangle and the zone where it intersects the horizontal line will tell you what kind of rock you have. Neat!

So what’s so interesting about granite? Well, it turns out there’s a lot.

**Granite is a magnetic encyclopaedia**

The crystals of feldspar and quartz which make up the majority of granite are sensitive to the Earth’s magnetic field (the magnetosphere) as they cool. Once they have solidified they contain a snapshot of the polarity and intensity of the magnetosphere which is called a paleomagnetic record. Provided the rocks aren’t contaminated by heat at a later date you can use them to read the strength of the Earth’s magnetic field billions of years ago. Smaller magnetic inclusions (the name given to the crystals) give more accurate results as they are less vulnerable to temperature changes.

John Tarduno of the University of Rochester used this property of granite to look at how the Earth’s magnetic field worked 3.2 billion years ago and found that the strength of the ancient field was at least 50 percent of the current one. That’s important because the magnetosphere is what protects the ozone layer from being destroyed by solar winds and the ozone layer protects the earth from the Sun’s harmful ultraviolet radiation. Without the magnetosphere life on earth wouldn’t be possible.

Another neat touch was that because the magnetic properties recorded by the crystals include the polarity of the Earth’s magnetosphere so Tarduno could check whether the rock had been contaminated at a later date by comparing the polarity with other samples of a similar age.

**Granite dominates the land, basalt owns the sea**

Both granite and basalt are igneous rocks, created when magma cools and solidifies but in terms of distribution, the continents are dominated by granite while the ocean floor belongs to basalt;. One of the differences between basalt and granite is that granite crystals are visible to the naked eye while basalt has much finer grains. This happens because on land the magma cools at a far slower rate giving the minerals time to grow larger while magma released underwater cools a lot faster making for teeny tiny crystals and that’s a massive part of why you will find granite on the continents but basalt in the ocean beds.

**Granite shows an ancient supercontinent linked the US and Antarctica**

A lump of granite found on the Nimrod Glacier near the Ross Ice Shelf in Antarctica had such a specific mineral composition that geologists were able to identify it as being related to a unique belt of rock which runs through parts of North America including California and New Mexico. The belt actually stops abruptly on the West Coast of the US hinting that a chunk of rock which used to be part of the supercontinent Rodinia — a precursor of Pangaea — had rifted away, eventually coming to rest in what is now Antarctica.

**Granite countertops can cause radiation exposure**

Most stone has the potential to emit radiation so the fact that granite can do so shouldn’t necessarily set alarm bells ringing, however granite has developed a bit of a radioactive reputation because some of its forms contain elevated concentrations of naturally-occurring radioactive materials.

Uranium 238 and thorium 232 are two such materials and can both cause radioactive gases like radon to be released into the surrounding atmosphere as they decay. In living areas — especially those with bad ventilation — the radon gas can accumulate and be inhaled potentially causing lung cancer.

Apparently there aren’t consumer guidelines for radiation safety when the emissions come from naturally occurring materials but using the safety standards which apply to controllable radiation sources a study by Daniel Steck of Saint John’s University in Collegeville, Minnesota (yeah, I had to look that up and check it wasn’t a spoof place name) discovered that putting lots of granite in small living spaces with poor ventilation can generate levels of radon which would be considered excessive.

The thing is, it depends completely on individual types of granite as to the level of risk. Most of the hoo-hah seems to focus around granite countertops and other home renovation materials but it also means that cellars carved into granite rock or towns built on granite foundations could experience radiation-related problems too.

**Granite radiation at Grand Central Station**

While writing this I found something which sounds suspiciously like an urban legend stating that the granite in Grand Central Station in New York emits more radiation than would be permissible at a nuclear power plant. After a bit of investigating it looks like this isn’t an urban legend but neither is it the cause for concern that it’s phrased as.

According to MIT the average annual background radiation dose for humans is 300 mrem and there’s a safe limit of 500 mrem for children and pregnant women. Grand Central exposes employees to 120 mrem per year (I don’t know how accurate that last figure is but it’s the only one I could find). That means that working at Grand Central will give you an annual radiation dose of around 420 mrem – still very much within the safe exposure zone for humans.

Basically, this all says more about the strict regulations governing nuclear power plants than it does about granite in Grand Central!