445g Fluorite & Calcite specimen – biting tips

This mineral specimen comes from Skardu, the main town of Baltistan in northern Pakistan and the starting point of the great expeditions to K2. Its character is defined by knife-sharp serrations and tips. Here two minerals with fundamentally different crystal languages meet: the strict order of cubic fluorite and the pointed forms of trigonal calcite. On one side, stair-stepped, intergrown fluorite cubes build up. They are glassy, gray to light blue depending on the light, and sometimes faintly lilac-tinged. Next to them rises a large, cream-colored calcite crystal, whose matte, rough surface bears growth and etching marks. From the front it looks like a fang of archaic power, from the back like a far-projecting, mountain-shaped tip. On the backside there is also a dense carpet of tiny calcite crystals over the fluorite, white to pale pink and sharp as knife blades. These crystals show the growth form known as dogtooth calcite, the scalenohedron. Its twelve faces are scalene triangles, hence the name, from the Greek skalēnos, “unequal.” That the fine teeth sit on the fluorite reveals the sequence of their formation: they crystallized first from later solutions, when the cubes had already formed. Across the specimen runs also a fine, rust-orange line of iron oxide. Both minerals are also reference minerals of the hardness scale that Friedrich Mohs established in 1812: calcite marks hardness 3, fluorite hardness 4. Stair-stepped cubes, a large calcite tooth, and the fine blade-like rug of the back: The specimen shows a different face from every direction and combines crystalline order with biting sharpness. A striking display specimen weighing 445 grams. Material: Fluorite (calcium fluoride, CaF₂) with calcite (calcium carbonate, CaCO₃) in dogtooth formation (scalenohedron) Origin: Skardu, Gilgit-Baltistan, Pakistan Dimensions: 10.5 x 6.9 x 5.6 cm Weight: 445 g Special features: Stair-stepped, intergrown fluorite cubes in gray to light blue, with occasional lilac undertone; large matte-cream calcite crystal with natural growth and etching marks; back with a dense carpet of fine, sharp-edged calcite scalenohedra on fluorite; fine iron oxide line across the specime

Estimation:€1

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