Tall slender amethyst geode from Brazil with a great chalcedony rim, goethite needles, and calcite

A 146 cm tall slender amethyst geode from Brazil with three collector-relevant accompanying minerals: a chalcedony rim, embedded goethite needles, and calcite accents. A four-mineral genesis in a stele-like geode piece.

The chalcedony rim is the microcrystalline quartz outer layer of the original geode, denser and finer than the amethyst lining inside. Goethite (FeO(OH)) is an iron oxyhydroxide that has grown into the amethyst wall as fine needles, giving the geode a reddish-brown color accent.

The calcite accents are the youngest mineral generation: after the completion of the quartz phase, calcium-carbonate-bearing solutions penetrated the residual cavity, allowing individual scalenohedral calcites to grow. Four mineralization phases in one 146 cm piece.

Brazilian geodes of this height dimension are classified as tower geodes in the collector trade. The recovery of intact slender tall formats requires particular caution from miners.

A collector's item with complex four-mineral genesis and a stele format.