Quartz is one of the most abundant and surprisingly complex minerals. It has many surprises as far as chemistry, formation, and ionic composition. This does lend for it to take on a great variety of shapes and to form in many different environments which ultimately lead to an abundance of different colors, inclusions, forms, associations and other characteristics.
Quartz traditionally falls into the Trigonal crystal system, however, beta-quartz is Hexagonal.
Quartz is Silicon Dioxide which is confusing to some as it is considered both a Silicate and an Oxide. It is structurally one and chemically the other. Here at NSC while we consider it to be either (or both) we do put Quartz in the realm of Silicates for purposes of simplicity.
What to look for: Perfection of Structure, Color, Inclusions, Luster, Specimens on Matrix, Associations, Internal Clarity, Isolation and Formation of Crystals, and Unusual Localities.