September 2025 – Moss agate

Moss agate owes its name to the fascinating patterns inside it, which are reminiscent of moss or small landscapes. However, these patterns are not caused by enclosed plants, but by fine inclusions of iron (red), magnesium and/or manganese compounds (brown, black, green).

Geologically speaking, moss agate is a variety of chalcedony, a microcrystalline form of quartz (SiO₂). It forms in cavities in volcanic rocks when silicic acid solutions slowly solidify. Moss agate has been valued as a gemstone and decorative stone for centuries. Each specimen is unique –a natural product that creates artistry without human intervention.

Chemical Formula: CaCu[OH|AsO₄]

Location: Deccan basalts, India