In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

Bloodstone, agate, and onyx are chalcedonic varieties of this mineral. Other color variations arise from substituting atoms for silicon; iron for citrine and amethysts, titanium for the rose variety. When cemented it makes sandstone and when fused, silica glass. For ten points, identify this mineral composed of crystalline silicon dioxide.
Science

This man put forth a theory on the formation of sentences intended to refute Hermann Pauls theory, using the example that, in the sentence Grass is green, our representation of grass contains our representation of green. He was given a typewriter as a gift by his student James Mckeen Cattell; he posited that the mind constructs psychic resultants which are formed by associations or apperceptive combinations. His first publication was Contributions to the Theory of Sense Perception, after which he formulated his theory of introspection, and then wrote Lectures on the Mind of Humans Animals. Another important idea of his is the tridimensional theory of feeling, discovered while employing physiological techniques in his famous laboratory. FTP, name this German-born Father of Experimental Psychology.
Social Science

A recent book discussing this nations Presidential election is You Must Set Forth at Dawn, which discusses the fraud at the heart of the administration of Umar Musa YarAdua. Recent troubles in this country have centered on a group partially led by Ateke Tom, which has been undertaking raids in its Rivers State near Port Harcourt, near a region from which Royal Dutch Shell employees have been kidnapped, the delta of its namesake river. For 10 points, name this oil-rich nation long ruled by Olusegun Obasanjo; a large nation of west central Africa.
History