Tectosilicate (framework silicate), zeolite, ferrierite group
Specific gravity: 2.154 calculated
Luminescence: Intense bluish white fluorescence under both short wave (254 nm) and long wave (366 nm) UV; such fluorescence is unusual for zeolites (CM 57.1.81-90).
Ferrierite-NH4 is a relatively new mineral, approved in 2018.
At the type locality, the Libous quarry, Březno, Chomutov District, Ústí nad Labem Region, Czech Republic, specimens containing ferrierite-NH4 were collected from a large, active open coal pit. The first analysed samples and the holotype were collected from the base of the main coal seam and occur there as radiating aggregates of elongated tabular crystals or fine fibrous aggregates with silky luster up to 1.5 mm across, consisting of very thin flattened prismatic crystals in fractures in abundant pelosiderite nodules in association with calcite, siderite, whewellite, quartz, opal, baryte and clay minerals. Later, occurrences of ferrierite-NH4 were also discovered in the hanging wall of the main coal seam. Above the coal seam there is a 1.5 m thick layer of dark brown carbonaceous shale with abundant small siderite concretions bearing radiating aggregates of ferrierite-NH4 (CM 57.1.81-90).
At the Bílina coal mine, Bílina, Teplice District, Ústí nad Labem Region, Czech Republic, specimens containing ferrierite-NH4 were collected from the southern part of the large, active open coal pit. It was found only in the proximity of the Bílina fault, in fractures of carbonate concretions, as well as in siderite and sandstone bands in the base of the main coal seam. Associated minerals are marcasite, pyrite, baryte, sphalerite and supergene gypsum (CM 57.1.81-90).
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