3" Lustrous Schorl and Goethite on Orthoclase Feldspar - Namibia

Schorl, also known as "black tourmaline" or "black schorl", is a black form of tourmaline that often occurs as lustrous prismatic crystals. The crystals can be stubby or elongated and typically feature lengthwise striations. Many schorl crystals have flattened pyramidal terminations. They can also form in radiating, columnar, and stalactitic aggregations, as well as small, needle-like inclusions within quartz (tourmalinated quartz) and in massive form.

Schorl is a basic sodium iron aluminum boro-silicate with the generic chemical formula NaFe2 + 3Al6(BO3)3Si6O18(OH)4 . It has been used for everything from jewelry to piezoelectric guitar pickups.

Aquamarine is a blue-green variety of beryl. Oddly enough, it owes its color to iron(II) and iron(III) cations within the crystal lattice, of which iron(II) is responsible for the blue color, while iron(III) is responsible for the yellow color. The color vibrance and hue are dependent on the concentration of these cations, or lack of one or the other. The presence of both cations in the right position within the crystal lattice, can result in a deep blue colored crystal that is known as "maxixe".