I read some comments that have the problem of understanding why the soldi composition at the end (T7) is An(80) Di(20), so I will try to explain in the following how these values come to be. 1. When you arrive at the Eutectic you will have a specific amount of Melt left, which you can calculate with the Lever Rule. (In this example we got roughly 35% Melt and 65% of Anorthite crystalls) 2. Now these last 35% Melt will form Diopside and Anorthite in a specific ratio. This specific ratio is the same as the one at the Eutectic. 3. We can now calculate the amount of Diopside and Anorthite which will crystallise from the 35% melt that is left, by multiplying the specific Ration with the amount leftover amount of melt. (for the Example in the Video: The amount Anorthite that will be formed is (0.35*0.42)*100 ≈14.7% The amount of Diopside: (0.35*0.58)*100=20.3% ) (DISCLAIMER: I know the values are a bit of, but the reason for that is that I cannot measure the exact points, because I dont have the Worksheet. But the method overall should be the correct and worked other examples completely fine.) 4. Now to get the end results for Anorthite, we have to add the 65% which crystallized before we reached the Eutectic to the 14.7% we calculated. For Diopside we allready got the end value of 20.3% because it did not crystallize before the eutectic. ( Total Anorthite: 14.7% + 65% = 79.7%) End Note: I hope for the people it will be clearer for the people that come here in the future. If anyone has a question just write it under the comment and I will try to answer it. (If you want to copy/share this, just try to fix my bad english before you do it. :P )
wow amazing video thanks. Your explanations are very straight forward and your english easy to understand (for me as a non native speaker). I wish I had just one professor who would explain stuff like that😢
@@kennethbefus ooh, interesting! I guess the role that pressure plays on phase transition differs quite a bit from one elements or molecule to another then. I want to learn a lot more chemistry and geology (and biology too). This is pretty cool stuff! So pressure has very little affect on the melting/precipitation point of these minerals then?
Pressure does have an effect. If another such experiment were carried out at a different pressure, the temperature values would be different. It is like the effect of pressure on the boiling point of water: at 1 atm, water boils at 100°C; but at 2 atm, it boils at 120°C.
Thank you very much; you really have helped me.
A little correction: at 17:49 composition of liquid is An 42 Di 58 (not Di 20).
One of the best petrology lecture on TH-cam.. Thanks alot!
NO CAP
I read some comments that have the problem of understanding why the soldi composition at the end (T7) is An(80) Di(20), so I will try to explain in the following how these values come to be.
1. When you arrive at the Eutectic you will have a specific amount of Melt left, which you can calculate with the Lever Rule. (In this example we got roughly 35% Melt and 65% of Anorthite crystalls)
2. Now these last 35% Melt will form Diopside and Anorthite in a specific ratio. This specific ratio is the same as the one at the Eutectic.
3. We can now calculate the amount of Diopside and Anorthite which will crystallise from the 35% melt that is left, by multiplying the specific Ration with the amount leftover amount of melt. (for the Example in the Video: The amount Anorthite that will be formed is (0.35*0.42)*100 ≈14.7% The amount of Diopside: (0.35*0.58)*100=20.3% )
(DISCLAIMER: I know the values are a bit of, but the reason for that is that I cannot measure the exact points, because I dont have the Worksheet. But the method overall should be the correct and worked other examples completely fine.)
4. Now to get the end results for Anorthite, we have to add the 65% which crystallized before we reached the Eutectic to the 14.7% we calculated. For Diopside we allready got the end value of 20.3% because it did not crystallize before the eutectic. ( Total Anorthite: 14.7% + 65% = 79.7%)
End Note:
I hope for the people it will be clearer for the people that come here in the future. If anyone has a question just write it under the comment and I will try to answer it.
(If you want to copy/share this, just try to fix my bad english before you do it. :P )
Wonderful! Very illumating and explicatory! Finally, I grasp how to really use the levver or leever rule!🙂
Thank you! You're the best man!
you saved my life bro thanks.
super helpful, thank you for this
thank you
This is great!
Thank you!
wow amazing video thanks. Your explanations are very straight forward and your english easy to understand (for me as a non native speaker). I wish I had just one professor who would explain stuff like that😢
I'm glad I could help.
Nice video！
How can you tell it's CLINOpyroxen in the first pic? Why not ortho?
how at eutectic point we get the same composition as initial..could you explain that for me...? y is it a equilibrium crysttn
One doubt.. How does 20% of Di get crystallized with just one drop(approx) of magma ?
What is the pressure? Is this just like sea-level atmospheric pressure then?
Constant pressure. could be 1 kb or 1 atm.
@@kennethbefus ooh, interesting! I guess the role that pressure plays on phase transition differs quite a bit from one elements or molecule to another then. I want to learn a lot more chemistry and geology (and biology too). This is pretty cool stuff!
So pressure has very little affect on the melting/precipitation point of these minerals then?
Pressure does have an effect.
If another such experiment were carried out at a different pressure, the temperature values would be different.
It is like the effect of pressure on the boiling point of water: at 1 atm, water boils at 100°C; but at 2 atm, it boils at 120°C.
I love u