DC-07. Mouseover the images to see a possible AFM diagram for this rock. To see a larger thin section image, click:






2.8e Questions (continued)

(5) There are 5 minerals (Sil-St-Grt-Bt-Pl) in sample DC-07, in addition to Ms+Qz, not the usual 3. What are some possible explanations?
Pick one and press "Enter".
(a) The mineral assemblage does not represent an equilibrium assemblage.
(b) The Grt has considerable MnO and CaO, increasing by two the number of components and, therefore, the number of possible phases at equilibrium.
(c) A chemical reaction among the minerals was stopped before completion by falling temperature, preserving both reactants and products.
(d) Water was not free to come and go (not a mobile component), increasing the number of componente and, therefore, the number of possible phases at equilibrium.
(e) All of the above are possible explanations for the extra minerals.