Creating a network and find out the name of a rock!

At the end of a week full of science, I had a touristic trip into the woodlands of Muir. Together with a geologist I met in San Francisco, I traveled to the forest with the large trees seen in the very famous bike chase scene in Star Wars on the second moon of Endor. It was a great trip and I can recommend it to anybody visiting the City of Fog.

The Muir Woods are situated in a valley, where the climate is much different than the surrounding mountain lands. So a geologist and a geophysicist could not resist to climb a mountain to the top (I say mountain, but they were large hills, except when I said that the giftshop woman gave me angry eyes). We decided to follow the Hillside trail, followed by the Ben Johnson trail. These trails gave us a good view of the forest and let us examine some really nice rock outcrops of the mountain. And on one of them I found this rock:



It is a greenish rock, which according to the geologist, could be serpentinite or an olivine containing rock (which I know now, serpentinite is as well, sort of :) ). Me, not being a geologist, wanted to know how he could deduce this. So I asked my fellow geologists I had met in Copenhagen (see this post for some details, not a lot). I posted the figure above and the following photo in our Facebook chat session (very modern, right):


This photo is a zoom-in of the crystal structure. My friendly-geologists from around Europe, started asking me questions about, what is the cleavage, the hardness and does it feel oily like? So I did a hardness test. My fingernail could not scratch it, so the rock hardness is >2.5 (on the Mohs scale), but a copper coin could make scratches on it, so its hardness is <3.5. The cleavage looked conchoidal according to some of the geologists (I'm still not sure how they could see this). Furthermore, I told them that the rock felt smooth, almost oily like. Therefore all the geologists in the chat group decided it should be SERPENTINITE!!! (a metamorphic rock originally containing a lot of olivine). 

This tells me that, if you don't know something, ask your network!

Reacties

Een reactie posten

Populaire posts van deze blog

Measuring the geoid. What is the geoid?

Afbeelding
During my weekly fitness session with one of my friends, we started discussing gravity (yes, also my friends are geeks (in the good way)). We discussed the measurements done by Vening Meinesz in the K18. He used I pendulum device, that directly measures the downward gravity attraction in the location of the device, plus all the motions of the device itself. On land, these motion are negligible, but on sea the device swings a lot due the ocean waves. Therefore, Vening Meinesz used a submarine to reduce the motions of the measurement device (waves are dampened underwater). Furthermore, he used three pendulums instead of one, which he ingeniously used to separate the motions of the device and the gravity attraction. Explaining this all to my friend, he remarked that it sounded very complicated and asked me if this could be done more easy. "Yes, this is possible", I replied, "with a GPS receiver". "How is it possible to measure Earth's gravity field with a GPS...
Meer lezen

How to make a spectrogram or waterfall plot

Afbeelding
In a few blogpost ago, I showed you several figures of a satellites transmission. You know, those beautiful S-curve plots with all the colours.  Those are called spectrograms or we like to call them waterfall plots, because the radio transmissions streams up in time like a reversed waterfall. To see such a waterfall plot live in action, the University of Twente opened their antennas for you to listen and see (see link ). Yet, how to make such a figure? To start with you need a recorded radio transmission. When the website of the TUDelft tracking station is up and running you can download some data there. However, (Start NerdAlert!) you can also buy your own little USB stick that acts like a software defined radio (SDR) receiver like the Logilink DVB-T . For only 20 euros you have your own satellite tracking station. NOTE: Beware! You need the RTL2832U chip version, because a lot of open software is written for that device. It is almost plug and play, you need some software, b...
Meer lezen

Interacting of the SDR with Matlab during my classroom tutorial

Afbeelding
This year was the second time I gave my tutorial with an SDR dongle. The idea behind this tutorial is to simulate ground-station-to-satellite interaction in the radiowave spectrum. The ground station is replaced by the SDR dongle and the student's computer. For the satellite, I use a radio beacon designed and built by a colleague of mine. The device transmits an FSK modulated signal at a certain frequency. During the tutorial, the students learn to develope software that interacts with the SDR, such that they can process the digital stream observed by the SDR. I made a small video of the signal with GQRX software, such that you can see the signal in the frequency spectrum and listen to the FSK modulation. Last year, I was using an open-source software package "gnuradio" for the signal processing part, but I found out that this introduced a lot of trouble-shouting in the first few hours, because of students having: different operating systems and versions (every s...
Meer lezen