1.9kg Oxidized Gold-Bearing Quartz Vein Specimen - eBay Rockley Rocks скачать в хорошем качестве

1.9kg Oxidized Gold-Bearing Quartz Vein Specimen - eBay Rockley Rocks

1.9kg Oxidized Gold-Bearing Quartz Vein Specimen from Historic Lachlan Orogen Orogenic Gold Mine, NSW Australia - Collector Grade Full Dossier on eBay Geological Dossier: Oxidized Quartz Vein Specimen from Lachlan Orogen Gold Province 1. Specimen Overview • Physical Dimensions: Approximately 18 cm (length) × 10 cm (width) × 9 cm (height), based on scale reference in accompanying photographs. The irregular, subhedral form suggests natural fracture surfaces with minimal post-collection modification. • Mass: 1,900 grams (1.9 kg). • Color and Texture: Predominantly milky-white quartz matrix with vuggy (cavernous) internal structure revealing open druses (crystal-lined cavities). Surface features extensive iron oxide staining in shades of ochre-yellow, rusty-brown, and localized black patina, indicative of supergene enrichment. Subtle brecciation (fragmented and recemented texture) is evident, with angular quartz fragments bound by oxidized matrix. No visible native gold to the naked eye, but micro-scale inclusions are probable given provenance. • Hardness and Density: Estimated Mohs hardness of 7 (quartz-dominant); bulk density ~2.65 g/cm³, consistent with low-porosity silicified vein material. • Condition: Excellent for a field-collected specimen—intact with no major fractures or repairs. Minor surface abrasion from handling/transport. This specimen exemplifies a classic “ironstone quartz” from orogenic gold systems, prized by collectors for its aesthetic contrast between the translucent white interiors and vibrant oxide exteriors. 2. Provenance and Collection Context • Locality: Sourced from an active or historic underground gold mine within the Lachlan Orogen (also known as the Lachlan Fold Belt), southeastern Australia. This vast Paleozoic terrane spans New South Wales (NSW), Victoria, and parts of Tasmania, with the specimen likely originating from the Central or Eastern sub-provinces (e.g., near Bathurst, Orange, or the Macquarie Arc). Specific mine undisclosed, but matches vein material from deposits like Cadia, Tomingley, or Garden Well—world-class producers yielding over 10 million ounces of gold historically. • Collection Date/Method: Field-collected by hand from a quartz vein exposure (inferred from irregular shape and fresh fracture faces). No chemical treatments or enhancements detected. • Legal/Ethical Notes: Australian-sourced; complies with export regulations under the Aboriginal and Torres Strait Islander Heritage Protection Act (1984). Suitable for international sale as a non-restricted mineral specimen. 3. Geological and Tectonic Setting • Orogen Age and Evolution: The Lachlan Orogen formed during the Middle Paleozoic (450–340 Ma), as part of the Tasman Orogenic System along the proto-Pacific margin of Gondwana. It represents an accretionary (“Andean-type”) wedge, where oceanic crust subducted beneath island arcs, leading to compressive folding and thrusting. Key deformational events include: • Benambran Orogeny (ca. 440–420 Ma, Late Ordovician–Early Silurian): Principal phase of gold mineralization, driven by slab rollback and arc magmatism. • Tabberabberan Orogeny (ca. 390 Ma, Middle Devonian): Regional metamorphism (greenschist to amphibolite facies) and upright folding of turbidite sequences. • Post-orogenic extension in the