That's a great question and probably requires a new video, which I'll try to record soon. In brief, An-Ab is a complete solid solution because there is no limit on the amount of Ab that can dissolve into An or vice versa. But An-Or is (highly limited) since only small amounts of Or can dissolve into An and vice versa (and Ab-Or is nearly complete at high T, but increasingly limited as T decreases).
No. Rock are collections of minerals. But the term "solid solution" only refers to minerals themselves, that have definite, but variable compositions. We can describe olivine as a mixture of Mg2SiO4 and Fe2SiO4 component formulas. And, ignoring minor elements, olivine varies between these two end members. There are no such definite formulas/components that can be used to describe rocks
@@keithputirka okay, I got it. One more (stupid) thing... I am trying to visualise the phrase 'solid solution'. The thing is I am not able to understand how they call it solid solution. In your video you gave an example of sodium chloride solution, in which I could see salt as solute, water as solvent and the resultant saline 'solution'. We could introduce potassium ions in the already formed saline solution. I was unable to imagine that happening in a solid solution because all I was imagining was two blocks of solids stacked one above the other and I was trying to imagine the elements getting exchanged (how Mg was replaced by Fe). I'm not able to quote my question properly (I feel like that), can you help me out? (Thanks for the response)
@@RajkiranRandhave Your questions are fine. I struggled with these same issues when I first studied mineralogy. Take your two blocks as an example, one being Mg2SiO4 and the other Fe2SiO4. Where the two blocks are in contact, they can mix. If temperatures are high enough to shake Mg and Fe out of their crystallographic sites and move through the lattice, the Mg and Fe atoms can switch sites, creating a solution of Mg and Fe at the interface. This solid state diffusion is slow and cm-size blocks might take millions of years to completely mix.
I like the demo with a litmus paper strip. Wet the strip then dip one end in acid and the other in alkaline.
What's the difference between a complete solid solution and a limited solid solution?
That's a great question and probably requires a new video, which I'll try to record soon. In brief, An-Ab is a complete solid solution because there is no limit on the amount of Ab that can dissolve into An or vice versa. But An-Or is (highly limited) since only small amounts of Or can dissolve into An and vice versa (and Ab-Or is nearly complete at high T, but increasingly limited as T decreases).
So a rock sample is nothing but a solid solution (right?)
No. Rock are collections of minerals. But the term "solid solution" only refers to minerals themselves, that have definite, but variable compositions. We can describe olivine as a mixture of Mg2SiO4 and Fe2SiO4 component formulas. And, ignoring minor elements, olivine varies between these two end members. There are no such definite formulas/components that can be used to describe rocks
@@keithputirka okay, I got it. One more (stupid) thing... I am trying to visualise the phrase 'solid solution'. The thing is I am not able to understand how they call it solid solution. In your video you gave an example of sodium chloride solution, in which I could see salt as solute, water as solvent and the resultant saline 'solution'. We could introduce potassium ions in the already formed saline solution. I was unable to imagine that happening in a solid solution because all I was imagining was two blocks of solids stacked one above the other and I was trying to imagine the elements getting exchanged (how Mg was replaced by Fe). I'm not able to quote my question properly (I feel like that), can you help me out? (Thanks for the response)
@@RajkiranRandhave Your questions are fine. I struggled with these same issues when I first studied mineralogy. Take your two blocks as an example, one being Mg2SiO4 and the other Fe2SiO4. Where the two blocks are in contact, they can mix. If temperatures are high enough to shake Mg and Fe out of their crystallographic sites and move through the lattice, the Mg and Fe atoms can switch sites, creating a solution of Mg and Fe at the interface. This solid state diffusion is slow and cm-size blocks might take millions of years to completely mix.
@@keithputirka This explanation really helped me render the image of solid solution! now I can sleep peacefully. Thanks a ton!
I like the demo with a litmus paper strip. Wet the strip then dip one end in acid and the other in alkaline.