Quartz

[SiO₂] Sample of pale violet to lavender, translucent amethyst [SiO₂] exhibiting characteristic cactus or spirit quartz growth habit. Larger, first-generation prismatic quartz crystals are encrusted along their prism faces by a second generation of numerous smaller, outward-projecting quartz crystals. These secondary crystals produce a drusy to finely spicular surface texture, while the terminations of several first-generation crystals remain exposed. The specimen displays local yellow-brown to orange colouration associated with the quartz overgrowth and matrix, possibly resulting from iron-oxide/iron-hydroxide staining or inclusions. Quartz has a Mohs hardness of 7, vitreous lustre, no cleavage, and commonly forms prismatic crystals with rhombohedral terminations. The distinctive secondary overgrowth exhibited by this specimen is commonly referred to as spirit quartz, cactus quartz, or pineapple quartz.