Brief Geology of Apophyllite

Описание: This mineral can be found within hydrothermal deposits, ancient lava, and basalt flows. It is most common to find Apophyllite in veins of gabbros and basalts that formed when the mineral was in a molten state. It also has a high water content. Apophyllite was once considered to be a single mineral, however, this mineral is now divided into two species of minerals: fluorapophyllite and hydroxyapophillite. These minerals form a solid solution where it allows fluorine to dominate over oxygen and hydrogen and vice versa. Although it is commonly believed that Apophyllite is a part of the Zeolite Group (Zeolites are network silicates belonging to the Tectosilicate Subclass), this is incorrect as Apophyllite is a layered Phyllosilicate. Its favorite crystal habit to grow in is the rectangular prism capped by a steep four-sided pyramid (tetragonal dipyramid).
Sources:
“APOPHYLLITE (Hydrated Potassium Calcium Sodium Silicate Fluoride Hydroxide).” Amethyst Galleries, 1995–2014, www.galleries.com/apophyllite.