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.

This god was suckled by a male boar and seawater when he was born at the edge of the Nine Worlds. In the Lokesenna, Loki says that this god has a muddy back and this god is also said to be the palest of all the gods. The name Gullintanni refers to this god's golden teeth. This god fathered the three (*) castes of man when he took the form of Rig. This god retrieves the Brisingamen for Freyja by transforming into a seal and defeating Loki. This god arrives at Baldr's funeral upon his horse Gulltopr and he wields the sword Hofund. This god is the son of nine mothers and kills and is killed by Loki at Ragnarok. For 10 points, name this Norse god that sounds his Gjallarhorn to signal Ragnarok, and is the guardian of Bifrost.
Social Science

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

One coefficient of this phenomenon can be found with Schlick's approximation, and its diffuse form is applied in Lambert's cosine law. This phenomenon notably does not occur for a certain polarization at Brewster's angle. At values above the critical angle, the (*) total internal type of this phenomenon occurs, and the law of it states that the angle at which this process occurs is equal to the angle of incidence. For ten points, identify this phenomenon in which a wave returns to its original medium after contacting a surface, easily observed with mirrors.
Science