Barite from Seddas Moddizzis Mine, Sardinia, Italy

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Classic Sardinian specimen with scalenohedral crystals of what were once calcite to 6.0 cm in height coming off matrix and now replaced by crystallized smithsonite as hollow casts. Minor barite is present. This is in excellent condition. The specimen was on public display at the 2026 Tucson Gem and Mineral show.A cast forms when one mineral fills the space left by another that has dissolved, preserving the external shape but not the original material. In the case of smithsonite after calcite, the original calcite crystals were removed by dissolution, and smithsonite later filled the resulting voids. The smithsonite takes on the crystal form of the original calcite, producing a cast rather than a true replacement. These specimens show the shape of calcite crystals but are composed entirely of smithsonite and are valued for preserving the original crystal geometry.The Seddas Moddizzis Mine in Sardinia, Italy, is a historic lead zinc mining locality that was worked mainly during the late 19th and 20th centuries. The deposit occurs in carbonate rocks and consists of hydrothermal mineralization with galena and sphalerite as the primary ore minerals. Mining was carried out through underground workings that followed the mineralized veins and replacement bodies. The mine is also known among collectors for producing mineral specimens from its oxidized zones. Operations eventually declined in the late 20th century, and the site is now part of the mining heritage of Sardinia.