*There are some edits in this post. My values for enstatite, wollostanite and ferrosilite were calculated incorrectly. New ternary diagrams were generated to reflect the update along with the new values.*
With finals coming up in the next few days, I really shouldn’t have put so much time into processing my meteorite data and making the ternary diagrams. Was it a complete waste of time? Not really. But I definitely could have been doing something school related. Oh well.
As I noted in the last post, I got to do a meteorite analysis with an electron microprobe last summer. It was a fun project, but it left me with a huge Excel spreadsheet of atomic weights, oxide weights and a host of other numbers and abbreviations that I didn’t understand. However, all that changed with my mineralogy course. After processing EMP data for the course lab, I did the same for my space rock data and created these spiffy ternary diagrams with Mystat.
A ternary diagram basically shows the proportion of elements in a certain mineral. Each mineral has a basic structure, such as Si2O6 for pyroxene, but they also incorporate a certain amount of magnesium, calcium and iron into their crystal structure. A ternary diagram allows you to display the quantity of each element and determine which kind of species of mineral you’re working with.
The first diagram displays the proportion of magnesium to calcium to iron in a pyroxene crystal. These values are also known as enstatite, wollastinite and ferrosilite, respectively. In the case of my little space rock, the dot on the graph tells us that it’s primarily a magnesium heavy pyroxene, at around
90% ( 78%).
Enstate/Ferrosilite/Wollostanite value for the pyroxene in the meteorite sample
The second graph displays the magnesium and iron ratio in the olivine crystals. The magnesium value is known as forsterite (Fo) and the iron value is known as fayalite (Fa). This graph is a little wonky because technically I should have three minerals and not two. But I decided to run with the diagram anyways and label the z-axis as C. It still shows what my spread sheet calculated: that the olivines are pretty magnesium rich, but still contain a fair amount of iron as well.
Eventually I’ll get some pictures of the meteorite posted as well.