"Store Didoni" Collection, Macherio (MB)

Typically found in Brazil (Minas Gerais), Madagascar, and Arkansas (U.S.), it is a quartz crystal with pyramidal faces at both ends of the crystallographic axis. Bitermination is relatively rare because most quartz crystals grow anchored to a wall or matrix, which prevents them from developing on one side: it forms when the crystal grows freely and suspended in a hydrothermal fluid (for example, in clay-filled cavities or in silica-rich fluids where the crystal detaches from its base), or through subsequent growth after detachment. Hexagonal prismatic crystal system, hardness 7 on the Mohs scale, density 2.65 g/cm³, vitreous luster. Specimens weighing over 10 kg, such as this one, belong to a particularly rare size category.

A piece with striking visual impact, sought after by collectors and museums for the rarity of its double-termination combined with its large size; it is used in high-end decorative settings, usually displayed vertically on a metal or wooden base; in crystal therapy, it is associated with balance and the flow of energy in both directions.