California State Gem Mine, Santa Rita Peak, San Benito County, California, USA
5,5×5,3×2 cm. (main crystal 4,7 cm long)
Superb specimen composed of excellent and lustrous Neptunite crystals, aesthetically arranged on a snow-white natrolite matrix; this is an eye-catching small cabinet, showing indubitable contrast due to its single well-formed Neptunite crystal, over 4,5 cm long. A San Benito classic piece with base included.
With the chemical formula ​KNa2​Li(Fe,Mn)2​Ti2​Si8​O24 Neptunite is one of the rarer and more striking minerals for both collectors and geologists. The discovery was attributed to swedish mineralogist Gustav Flink in 1893 who called it neptunite after the Roman god Neptune, due to its association with aegirine, which is linked to the Norse sea god Ægir. The first known occurrence of neptunite was in the Narssârssuk pegmatite in Greenland (type locality) so Gustav Flink is the accepted discoverer; however we note that in the same year, in the San Benito area, the mineral was also identified by a group of American mineralogists led by George F. Kunz and, at the same time, from Dr. L. G. Graton. Its prismatic, elongated crystals are typically well-formed and can reach a good size, especially in its most famous locality. Normally black, the iron (Fe) in neptunite can be replaced by manganese (Mn), resulting in slight variations in properties and color, ranging from black to dark reddish-brown. Due to its scarcity and attractive appearance, especially in conjunction with Benitoite, this rare silicate is highly sought after by mineral collectors. Neptunite typically forms in alkali-rich environments such as pegmatites or within serpentinites and associated metamorphic rocks. It is most often found in association with other rare minerals, such as Benitoite and Natrolite, which occur in similar geochemical environments, and mainly comes from the San Benito mines in California, a region that has produced extraordinary and aesthetically pleasing specimens of these minerals over time, highly prized by collectors.
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