The Hatrurim Basin, Israel, is located on the western border of the Dead Sea Transform. This is one of the localities of a unique pyrometamorphic complex whose genesis remains problematic. This paper deals with zeolite-bearing rock that is known in the Hatrurim Basin only. The strata subjected to zeolitization is called the “olive unit” and consists of anorthite–pyroxene (diopside–esseneite) hornfels. Zeolitization occurred in an alkaline environment provided by the interaction of meteoric water with Portland-cement-like rocks of the Hatrurim Complex. The resulting zeolite-bearing rocks contain 20–30% zeolitic material. The main zeolitic minerals are calcic: thomsonite-Ca ± Sr, phillipsite-Ca, gismondine-Ca, and clinoptilolite-Ca. The remainder is calcite, diopsidic pyroxene, garnets (either Ti-andradite and/or hydrogrossular), and less frequently, fluorapatite, opal, and others. Their major mineralogical and chemical compositions resemble carbonated zeolite-blended Portland mortar. Rocks show different values of porosity. Their mechanical characteristics are much better for samples with porosity values below 24%. The related parameters are like those of blended concretes. The minimal age of zeolitization is 5 Ka. The natural zeolite-bearing rocks are resistant to weathering in the Levant desert climate.

A new mineral, gismondine-Sr with ordered gismondine framework type [B2212 no. 20, Z = 1; a = 14.0256(2) Å, b = 10.45900(10) Å, c = 13.79360(10) Å, V = 2023.44(4) Å3] and the ideal chemical formula Sr4(Si8Al8O32)·9H2O was discovered in amygdaloidal voids of partly melted gehlenite hornfels at Halamish locality, Hatrurim Basin of the Hatrurim Complex, Negev Desert, Israel. Gehlenite horn-fels is mainly composed of gehlenite, wollastonite, and garnet of the grossular-andradite-schorlomite series. In a low-temperature association occur minerals such as thomsonite-Ca, flörkeite, analcime and minerals of the tobermorite supergroup. Gismondine-Sr forms spherulitic aggregates up to 180 μm and, rarely, pseudotetragonal bipyramidal crystals up to 50 μm. Empirical crystal-chemical formula of gismondine-Sr is (Sr2.02Ca1.09Ba0.02K0.72Na0.62)Σ4.47Al7.91Si8.09O31.85·9H2O. It is the strontium analog of gismondine-Ca and the second orthorhombic zeolite with the GIS structure topology. Crystals are transparent to translucent and feature vitreous luster. The mineral exhibits a white color, imperfect cleavage in [101] direction, a brittle tenacity, and uneven fracture. The Mohs hardness was estimated at approximately 4. Gismondine-Sr is biaxial negative, α = 1.488(3), β = 1.492(3), γ = 1.495(3), 2Vobs = 70–80°. The Raman spectrum is characterized by a band at 465 cm−1, which is also the main band in gismondine-Ca. The structure refinement using SC-XRD (R1 = 0.0353) reveals the ordered distribution of framework cations and the disordered arrangement of extraframework cations. The aluminosilicate framework is built by crankshaft chains with 8-membered apertures channels parallel to [101] and [101]. In gismondine-Sr, the 8-membered rings are elliptically deformed and the T-O-T angle of the upward and downward tetrahedra in the double crankshaft chains is smaller compared to that for gismondine-Ca. Consequently, a slight rotation of the double crankshaft chains has been noticed. Similar observations have been made in partially dehydrated and the pressure-modified gismondine-Ca. The present study suggests that, in addition to high-pressure and dehydration, the elliptical deformation of the channels in GIS also arises as a consequence of the extraframework cations and H2O content. Thus, the extraframework content influences the aluminosilicate framework leading to the orthorhombic symmetry.

Fluoralforsite, ideally Ba₅(PO₄)₃F, (space group P6₃/m (#176), Z = 2, a = 10.0031(2) Å, c= 7.5382(2) Å and V = 653.23(3) ų), is a new mineral species of the apatite group – a Ba-analogue of fluorapatite and a F-analogue of alforsite. It was discovered in rankinite paralava filling cracks in pyrometamorphic gehlenite hornfels near the tributary of wadi Zohar and Gurim Anticline, Hatrurim Basin, Negev Desert, Israel. Fluoralforsite occurs in small intergranular spaces between large gehlenite and garnet crystals and in enclaves inside large rankinite crystals with other Ba minerals such as walstromite, zadovite, bennesherite, gurimite, mazorite, barioferrite and baryte. It forms tiny transparent, colourless crystals up to 50 μm with a white streak and a vitreous lustre. The cleavage was not observed. It exhibits a brittle tenacity and a conchoidal fracture. The estimated Mohs hardness is 4–4½, and its calculated density is 4.57 g/cm^–3. Fluoralforsite is uniaxial (–) with refractive indices (589 nm) n_ω = 1.689(3) and n_ɛ = 1.687(3). The empirical crystal-chemical formula for the holotype calculated on the basis of 8 cations is: (Ba_3.81Ca_0.97Na_0.07K_0.05Sr_0.05Fe_0.05)_Σ5(P⁵⁺_2.32V⁵⁺_0.29S⁶⁺_0.22Si_0.17)_Σ3O₁₂(F_0.85Cl_0.13)_Σ0.98. The crystal structure was refined from single-crystal X-ray diffraction data with R₁ = 0.0192. The structural investigation indicated an ordered arrangement of Ba/Ca at the M1 site within individual columns running along the c-axis, but a disordered distribution among adjacent columns throughout the structure, which enables the maintenance of the P6₃/m space group. Fluoralforsite was formed at the final stage of crystallisation as a result of a reaction between the primary mineral assemblages and residual melt.

Flörkeite, a rare zeolite with PHI (phillipsite) framework type, was found in numerous amygdaloidal voids in pyrometamorphic rocks of the Hatrurim Basin, Hatrurim Complex, Israel. This is the second reported occurrence of flörkeite previously found in a Ca-rich xenolith from a quarry at the Bellerberg volcano near Ettringen, East Eifel volcanic area, Germany. The mineral with the empirical crystal chemical formula (K_2.91Ca_2.00Na_0.91)[Al_7.96Si_8.04O_31.94]·12H₂O (P-1, no. 2, $a=19.93662$⁠, $b=14.25171$⁠, $c=8.8935010Å$⁠, $α=88.24801$⁠, $β=125.096010$⁠, $γ=89.635010$⁠, $V=2019.194Å3$⁠, and $R=3.41%$⁠) did not show significant differences with respect to that of the type locality. The Raman spectrum of flörkeite is here reported for the first time. No significant differences are noticed compared to phillipsite-K. The main band ~470 cm^-1, characteristic of the PHI-type structures, is independent on framework order and Si/Al ratio. The zeolite mineralization of amygdules in pyrometamorphic rocks results from meteoric water circulations in Al-rich rocks during their cooling. The crystallization sequence of zeolite corresponds to the Ca/(K+Na) ratio decrease. Flörkeite formed at the end of a low-temperature crystallization sequence, indicating the predominant role of potassium in crystallization. The occurrence of flörkeite in different pyrometamorphic rocks implies the relatively uniform, regional mineral-forming conditions, and open hydrologic system of zeolitization. In pyrometamorphic rocks of the Hatrurim Basin, the process of zeolitization is characterized by low silica activity and high pH conditions.

Orange greenockite (CdS) aggregates were found in a small fumarole at a burned coal dump near Bytom, Upper Silesia, Poland and were studied using a variety of techniques in order to determine their chemistry, morphology, and most importantly, the mechanism of crystal growth. Greenockite rods, wires, and whiskers with bismuth drops on crystal tops are predominant in these aggregates. Greenockite rods oriented sub-perpendicular to the substrate surface. The rod thickness reaches 5–6 μm and about 10 μm in length. The catalyst bismuth drop has a diameter comparable to the rod thickness. Fiber forms (wires and whiskers) are sub-parallel to the substrate surface. The thickness of these forms is usually less than 2 μm, and the length can be close to 1 mm. The bismuth drop diameter can show a large excess over the fiber thickness. Catalyst drops on the tops of whiskers began to change their form dynamically and exploded, spraying bismuth under the electron beam effect. Rods grow along the [01–10] direction, and whiskers and wires (axial forms) along the [0001] direction. Greenockite rod crystals, carrying on top a relatively homogenous bismuth catalyst drop, were formed on the heated substrate according to the VLS (vapor–liquid–solid) mechanism at temperatures not lower than 270 °C. Greenockite whiskers and wires grew just above of the substrate surface according to the VQS (vapor–quasiliquid–solid) mechanism at temperatures lower than 200 °C. These mechanisms of growth have very rarely been recorded to occur in nature and even less so in burning coal dumps. The cooperative growth effects of the fiber greenockite crystals were also described.