Deep purple amethyst on brass base

Amethyst from Uruguay on a brass base. So, with small crystals usually. Amethyst is a type of purple quartz, with magmatic origin. Its name comes from the Greek Amethustos «which preserves from drunkenness» because its colour evokes wine diluted with water.
It is found in cavities formed millions of years ago by ancient gas bubbles frozen in lava, where a very hot water concentrated in silica and iron minerals has circulated. It is the quantity of these diluted minerals as well as their type, which determined the color of these sublime crystals.
As it cooled down, the water left deposits on the walls of the cavities, transformed into beautiful geodes of purple crystals, with the time.