According to the Perceived Service Quality model (Figure 1), the quality of a service, as perceived by the customer, is the result of a comparison between the expectations of the customer and his or her real-life experiences.
Resorption of garnet I may have occurred either as a result of the prograde univariant reaction Grt + Chl + Ms = St + Bt + Qtz + H2O, or during decompression, by the net transfer reaction Grt + Ms + H2O = St + Bt + Qtz, before staurolite had become unstable.
Obsidian is formed in the Igneous phase of the rock cycle. Its formed as a result of rapid cooling of erupted lava, Obsidian also referred to as Volcanic Glass is an Extrusive Igneous Rock and comes to existence when lava at the earth surface cools at a very fast rate that its crystallization stage hardly comes to play, it appears as a massive rock that is very fine and smooth to touch, and glassy in appearance.