{"product_id":"autunite-sao-pedro-malacacheta-minas-gerais-brazil","title":"Autunite - Sao Pedro, Malacacheta, Minas Gerais, Brazil","description":"\u003cp data-start=\"186\" data-end=\"791\"\u003e\u003cstrong data-start=\"186\" data-end=\"198\"\u003eAutunite\u003c\/strong\u003e is a secondary uranium phosphate mineral with the chemical formula \u003cstrong data-start=\"266\" data-end=\"293\"\u003eCa(UO₂)₂(PO₄)₂·10–12H₂O\u003c\/strong\u003e, formed through the oxidation and alteration of primary uranium-bearing minerals in the near-surface environment. This specimen displays classic \u003cstrong data-start=\"439\" data-end=\"477\"\u003etabular to lamellar crystal growth\u003c\/strong\u003e, stacked in thin, platy sheets with sharp, stepped edges—a hallmark of well-crystallized autunite from Brazilian pegmatitic and hydrothermal systems. The vivid \u003cstrong data-start=\"638\" data-end=\"675\"\u003eyellow to yellow-green coloration\u003c\/strong\u003e is caused by the presence of the uranyl ion (UO₂²⁺), which also gives the mineral its exceptional visual intensity.\u003c\/p\u003e\n\u003cp data-start=\"793\" data-end=\"1383\"\u003eGeologically, autunite forms in the \u003cstrong data-start=\"829\" data-end=\"899\"\u003eoxidation zones of uranium-rich pegmatites and granitic host rocks\u003c\/strong\u003e, where circulating groundwater reacts with uranium minerals and phosphate sources. The São Pedro–Malacacheta region in Minas Gerais is known for complex granitic intrusions and pegmatites enriched in rare elements, providing ideal conditions for secondary uranium mineralization. The fragile, micaceous texture of this specimen reflects its \u003cstrong data-start=\"1241\" data-end=\"1283\"\u003elow hardness (2–2.5 on the Mohs scale)\u003c\/strong\u003e and perfect cleavage parallel to the crystal plates, making intact examples particularly desirable.\u003c\/p\u003e\n\u003cp data-start=\"1385\" data-end=\"1928\"\u003eUnder \u003cstrong data-start=\"1391\" data-end=\"1421\"\u003elongwave ultraviolet light\u003c\/strong\u003e, this specimen exhibits a strong \u003cstrong data-start=\"1455\" data-end=\"1482\"\u003eneon green fluorescence\u003c\/strong\u003e, a diagnostic feature of autunite resulting from uranyl activation. The mineral is \u003cstrong data-start=\"1566\" data-end=\"1581\"\u003eradioactive\u003c\/strong\u003e, though typically at low levels for small specimens, and is stable only in relatively dry conditions—over time, autunite can dehydrate and transition into meta-autunite. Overall, this piece represents a fine example of \u003cstrong data-start=\"1801\" data-end=\"1840\"\u003esecondary uranium mineral formation\u003c\/strong\u003e, combining geological significance, regional provenance, and striking aesthetic appeal.\u003c\/p\u003e\n\u003cp class=\"p1\"\u003e\u003cb\u003e**Specimen from historic collection of Luiz Menezes, one of Brazil’s most respected mineral collectors from Brazil**\u003c\/b\u003e\u003c\/p\u003e\n\u003cp class=\"p1\"\u003eApproximate measurements: 14.42 x 8.12 x 7.13 mm\u003c\/p\u003e\n\u003cp class=\"p1\"\u003eWeight: 0.93 g\u003c\/p\u003e","brand":"LOLO TERRA","offers":[{"title":"Default Title","offer_id":46908094578858,"sku":"LU-SP-52-11\/20634","price":180.0,"currency_code":"USD","in_stock":true}],"url":"https:\/\/www.loloterra.com\/products\/autunite-sao-pedro-malacacheta-minas-gerais-brazil","provider":"Lolo Terra","version":"1.0","type":"link"}