Graphite is identified in a particular schist. Which one of the following conclusions is justified?
A) The graphite lubricated shearing movements along a fault, causing a schist to form.
B) The rock also contains diamonds; both are crystalline forms of the element carbon.
C) The pre-metamorphic rock was a shale or mudstone containing organic matter.
D) The schist formed from a quartz-rich, sedimentary limestone.

Question

Quizplus · Accepted Answer

Graphite in schist suggests that the original rock contained organic matter, which, under high pressure and temperature conditions during metamorphism, transformed into graphite. Shale or mudstone, rich in organic material, is a common precursor for such metamorphic rocks.

Graphite Is Identified in a Particular Schist