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  1. binomania

    Real calcium fluorite in NL binoculars?

    Hi, here's an excerpt from my old review regarding Kowa Prominar 8.5x44 (by google translate..sorry) Mineral fluorite The fluorite mineral is a halide of the monometric group has a hardness equal to 4 a specific weight: 3.1-3.2 and a refractive index: n = 1.433, it emits light when heated...