Uruguay amethyst with stalactites on brass base

Amethyst from Uruguay on a brass base. Amethyst is a type of purple quartz, with magmatic origin. 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 time.
And exceptionally, stalactites did occured. Here we cut and polished a part of them to highlight their internal structure.