Acta Musei Moraviae

New finds of zeolite mineralization from the historical locality Janovice (Moravia, Czech Republic)

In 2019, new finds verified the occurrence of zeolite mineralization from the historical locality Janovice (Rábl quarry) and in its vicinity (occurrence in the field above the quarry). Until then, the locality was generally considered extinct. The locality is situated 1 km SW of Janovice, 1.4 km NE of Palačov and approximately 800 m NW of Petřkovice; Moravia (Czech Republic). Zeolite mineralization is mainly represented by natrolite, less analcime and the newly described rare harmotome. The average empirical formula of zeolites corresponds to published data: natrolite – Na_2.01[Al_1.98Si_3.02]Σ₅O₁₀ · 2H₂O; analcime – Na_0.98[Al_0.95 Si_2.04]Σ_2.99O₆ · H₂O; harmotome – (Ba_1.74Ca_0.35K_0.18Fe_0.08)Σ_2.35[Al_4.85Si_11.21Ti_0.03]Σ_16.09 O₃₂ · 12H₂O. Zeolites were also verified by X-ray powder diffraction with unit-cell parameters: a = 18.337(6), b = 18.565(5), c = 6.583(2) Å and V = 2241.9(5) ų (natrolite); a = 13.718(3), c = 13.6967(1) Å and V = 2577.5(5) ų (analcime); a = 9.876(5), b = 14.138(4), c = 8.695(7) Å, β = 124.82(5)° and V = 996.7(8) ų (harmotome). Abundant calcite in several types and generations, and rarely baryte and quartz, have been found as associating minerals. Minerals represent fillings of cavities and fissures in the picrites of the Hradiště Formation of the Silesian Unit, Western Carpathians. Due to the secondary position of most finds (dumps of crushed rocks) and or finds from subsurface parts of occurrence in the field above the quarry, it is not possible to specify the primary geological position of zeolites in the body of picrite. This finding is especially significant for the larger number and high quality of the samples found, which are comparable to historical findings from the late 19th century and the first half of the 20th century.