Mineralogical, Geochemical, and Rock Mechanic Characteristics of Zeolite-Bearing Rocks of the Hatrurim Basin, Israel

: 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 classical description of the mineralogy of the Hatrurim Complex also includes zeolites [7].In different rock types of the Hatrurim Basin, a researcher determined Carich thomsonite, phillipsite, and gismondine were the most common or rock-forming Ca-rich zeolites, including several chemical analyses of thomsonite-Ca and gismondine-Ca.Minor minerals of the Ca-rich zeolite family were identified as scolecite, mesolite, heulandite, epistilbite, gmelinite-Ca, and lévyne-Ca.Ba-zeolite, harmotome, was also reported.Analcime occurs sporadically.There is a wide diversity of zeolites in different rocks of the Hatrurim Basin.Recently, one more type locality mineral, gismondine-Sr, was approved by CNMNC-IMA [8].
In the present report, we describe the mineralogy, chemistry, and mechanical parameters of zeolite-bearing rocks sampled at Mt. Ye'elim.The occurrence of zeolite-bearing rocks in the Upper Cretaceous sedimentary cross-section of Israel, composed mainly of chalks and marls, is unusual.Zeolite-bearing rock formation occurs without any relation to volcanic or feldspathic precursors.This rock contains from 18 to 30 vol.% of zeolites.Among them, phillipsite-Ca, gismondine-Ca, and thomsonite-Ca are predominant.The composition of the rocks makes them analogous to zeolite-blended Portland mortar.Due to the similarity of the natural zeolite rocks to carbonated zeolite-blended Portland mortars, we have studied their rock mechanical parameters.The study of these parameters is useful for the prediction of durability and mechanical stability of the latter industrial material.

Geological Setting
Zeolite-bearing rocks are common in the Hatrurim Basin, Negev Desert, Israel.The Hatrurim Basin is the largest outcrop of the Hatrurim Complex (also known as the Mottled Zone) in Israel.It covers an area of about 50 km 2 .The outcrops of the Hatrurim Complex are known in Israel and Jordan, near the Dead Sea Transform Fault (Figure 1A).The Hatrurim Complex is mainly composed of ultra-and high-temperature pyrometamorphic rocks metamorphosed at the conditions of sanidinite facies and products of their lowtemperature alteration [9].Blackish-and reddish-colored ultra-and high-temperature rocks form lenses and cliffs embedded into a matrix of light-colored, low-temperature rocks.The main types of high-temperature rocks are represented by spurrite, gehlenite, larnite marbles, and anorthite-pyroxene hornfelses.Low-temperature rocks are mainly composed of calcium hydro-silicates and carbonates.Lenses of high-temperature rocks (spurrite-bearing ones) are, in some cases, huge, up to 12 m in thickness and up to a 200 m × 200 m plane.In old quarries, the continuous thickness of spurrite-bearing rocks can be more than 30 m.
The common temperature of metamorphism was in the range of 600-900 • C.However, the revealing of numerous types of paralavas and direct study of melt inclusions indicated that the local temperatures were as high as 1200-1450 • C [12].Thus, the typical appearance of the outcrops bears a resemblance to multi-colored hummocky relief, from which originated the second term describing the Hatrurim Complex: the Mottled Zone.
The Mottled Zone is classified as a pyrometamorphic complex.One of the most popular hypotheses of its genesis [13] is the combustion of dispersed organic matter in the chalky-marly sequence of the Maastrichtian and Paleocene Age (Figure 1B).Fascinating mineralogical assemblages in rocks and their weathering products account for more than 240 mineral species.Most of them are rare or extremely rare, the Hatrurim Basin being the type locality for more than 20% of them (e.g., [14][15][16]).
According to field observations, the thickest-ca.100 m-pyrometamorphic crosssection, composed mainly of the chalky Ghareb and chalky-marly Taqiye Formations, is preserved in the Hatrurim Basin (Figure 1B,C).Due to its mainly greenish color, the metamorphosed equivalent of the Taqiye Formation is locally termed the "olive unit" (Figure 1C).It is not recognized in other outcrops of the Hatrurim Complex.It predominantly covers the tops of the highest hills in the Hatrurim Basin (Figure 2) [17].The outcrops are up to a few hundred square meters 10-30 m in thickness.According to a geochemical comparison, the olive pyrometamorphic rocks correlate to lower marly members of the Taqiye Formation [18].The Taqiye Formation shows a uniform lithological character with gypsum veins, pyrite, and baryte concretions.Its detrital clay assemblages are composed of montmorillonite (40-80%), kaolinite (20-50%), and illite (0-20%) [19].The pyrometamorphic equivalent of the marly sequence of the Taqiye Formation is commonly composed of anorthite-pyroxene hornfels (Figure 1D), with ferrite segregations, baryte concretions, enclaves of coarse-grained pyrometamorphic rocks, glassy and/or vesicular-like paralavas, and low-temperature zeolite-bearing rocks.According to the glass composition of paralavas and corundum-hematite pairs revealed in ferrite enclaves, temperatures of pyrometamorphism of the olive unit were locally as high as 1000-1200 • C [20,21].
Several types of rocks compose the olive unit, whereas the process of zeolitization is chiefly related to anorthite-pyroxene hornfels.Anorthite, diopside-hedenbergite, gehlenite with grossular and vesuvianite or wollastonite were previously determined in hornfels of the olive unit [7].
In several cases, pyrometamorphic rocks of the olive unit are completely replaced by zeolite-bearing rocks.The zeolitization looks like a mantle topping several hills in the northern part of the Hatrurim Basin (Figure 2).Rare cliffs indicate that the zeolitized zones are at least a few meters thick.Zeolitic rocks are easily recognized by their light yellow color and porous texture of the fresh surface, whereas outcrops show brown or reddish patina.Baryte concretions up to 10 cm across and hematite nodules up to a few cm across are common (Figure 1E).
In a row of outcrops, there are recognizable relics of the high-temperature rocks within the zeolite-bearing zone of alteration.Gradual conversions of high-temperature rocks into the zeolite-bearing ones are common.Some cliffs of the anorthite-pyroxene hornfels are rather fresh and almost not subjected to zeolitic alteration.
According to 40 Ar/ 39 Ar dating on whole-rock, acid-insoluble residue fractions, and a gehlenite mineral separate, the major combustion event occurred in Israel around 3 Ma [22]. 230Th-234 U dating was performed of carbonate-bearing veins in spurrite and gehlenite marbles.The ages of most veins are in the 250-30 Ka range.Isotopic data on δ 13 C (−18‰ to −5‰) and 87 Sr/ 86 Sr (0.70786-0.70811)ratios indicate the interaction of meteoric waters with pyrometamorphic rocks during the formation of carbonate veins [23].
The range of carbonate veins ages roughly corresponds to intensive weathering in the southern Levant during interglacial periods [24].If the similar process and ages are correct, then the youngest limits of the zeolitization process are about 30 Ka.It is not excluded that the zeolitization may be related to wet climatic conditions in the Dead Sea basin between 6.3 and 3.3 Ka BP [25].
The zeolite-bearing blocks, such as dimension stones, from the talus slope of Mt.Ye'elim (Figure 2) have been selected for the present study.The chemical, mineralogical, and rock mechanic parameters were obtained on homogeneous parts of blocks deficient in the baryte concretions and hematite nodules.
Powder X-Ray Diffraction (PXRD)-the major phase analysis tool-was used to obtain information about mineralogical composition of the rocks.The analyses were performed using a Bruker AXS D8 Advance diffractometer at the Clay Minerals Laboratory, Institute of Geological Sciences, Polish Academy of Sciences, Kraków, Poland.The diffractometer was equipped with a superfast LPS (linear-position-sensitive) VÅNTEC-1 detector.The radiation was CoKα, filtered and not monochromatized.The 3-80 2θ range was scanned, with 0.02 increment; 1 s per step counting time was used (in the scintillation detector language; equivalent of 416 s per step in the LPS detector language).Unit-cell parameters and crystallite size were refined using the Rietveld method ( [26]) in the Topas software (v.4.0).
Correctness of the approach used was verified by the attendance of one of us (Ł.K.) in Topas course, Rietveld Mailing List, and the Reynolds Cup 2018 competition.
To support the above chemical and mineralogical research, Raman Spectroscopy was also applied.The Raman spectra were recorded on a WITec alpha 300R Confocal Raman Microscope (Institute of Earth Science, Faculty of Natural Sciences, University of Silesia, Sosnowiec, Poland) equipped with an air-cooled solid laser 488 nm or 532 nm and a CCD camera operating at −61 • C. The laser radiation was coupled to a microscope through a single-mode optical fiber with a diameter of 3.5 µm.An air Zeiss LD EC Epiplan-Neofluan DIC (100/0.75NA)objective was used.Raman scattered light was focused on a broad band single-mode fiber with effective pinhole size about 30 µm and monochromator with a 600 mm −1 grating.Integration times of 3 s to 5 s with accumulation of 10-20 scans and a resolution ca. 3 cm −1 were chosen.The monochromator was calibrated using the Raman scattering line of a silicon plate (520.7 cm −1 ).
Mechanical properties of sixty-three zeolite samples were defined at Rock Mechanics Laboratory (Ben-Gurion University, Be'er Sheva, Israel).All samples were oven-dried prior to testing at the temperature of 105 • C for 24 h.Twenty-three samples were used for point load tests, twenty-three samples for tensile (Brazilian) tests, seven samples were subjected to uniaxial and triaxial compression, and ten were exploited for definition of grain density.Point load index (I d ) and tensile (Brazilian) strength (σ t ) were measured by using a standard Point load/uniaxial Tester (SBEL model PLT-75) equipped with hydraulic hand pump (with pressure capability of 70 MPa) and gauge for measurement of applied axial load.A stiff load frame (Terra-Tek, model FX-S-33090) was used for definition of peak axial stress (σ 1p ) of rock samples under compression.The frame utilizes a closed-loop, servo-controlled hydraulic system with maximum axial force of 1.4 MN and stiffness of 5 × 10 9 N/m [27].The elastic modulus (E) and Poisson's ratio (ν) were calculated using linear regression along the liner segment of the compressive stress-strain curve.Grain density (p g ) was measured by using helium porosimeter PH-220.We measured grain volume, and then pore volume was defined by difference between bulk volume of the sample and grain volume.

Bulk Chemical Analyses of the Zeolite-Bearing Rock
The chemical analysis of zeolite-bearing samples is shown in Table 1.The geochemical comparison of zeolite-bearing rock and hornfels of the olive unit is shown in Figure 3.At LOI about 15% (a diagonal line on Figure 3), zeolite-bearing rocks show similar content of SiO 2 and Al 2 O 3 and enrichment in CaO.They are also enriched in Mn and Cr.Zeolite-bearing rocks are depleted in K 2 O, Sr, and Zn.Depletion of Ba is related to the omission of baryte concretions from the analyzed matter.

Mineral and Chemical Composition of the Zeolite-Bearing Rock
The PXRD analysis coupled with SEM-EDS and EPMA methods and Raman analysis allows us to unequivocally recognize the mineral composition of the studied samples.According to the PXRD phase quantitative analyses (Table 2), it was established that calcite is the dominant phase in all the studied samples, and its basal reflection has a surplus intensity due to calcite's well-known preferred orientation.This issue was corrected with the use of the March-Dollase approach.It is followed by a phase with a clinopyroxene (diopside) structure in abundance.Additionally, garnet is the main constituent in most of the samples.These three minerals account for more than 70% of the rock volume.Phillipsite-Ca, gismondine-Ca, thomsonite-Ca, and opal are minor minerals in the studied rock.Fluorapatite, garronite-Ca, pumpellyite-group species, amesite, ferrierite-K, clintonite, clinoptilolite-Ca, and baryte are present in insignificant amounts.It should be noted that some differences in the rock composition are caused by the uneven distribution of minerals in the volume of the rock and may depend on the chosen fragment of the rock (Table 2).According to SEM data, calcite, opal, gismondine-Ca, thomsonite-Ca, phillipsite-Ca, and pyroxene of the diopside-esseneite series and garnet of the grossular-andradite series are the main minerals comprising the studied rocks (Figure 4).Pyroxene and garnet usually form anhedral-and very rarely euhedral-grains and crystals up to 40 µm in size as a rule.It is very seldom that garnet aggregates reach about 100 µm.Euhedral crystals are represented by poikilitic crystals looking almost homogenous and showing the medium composition between grossular and andradite.EPMA analysis revealed that in some cases, such crystals contain a thin, irregular, discontinuous external zone slightly enriched in Fe and Ti (up to 2 wt.%TiO 2 , Table 3).Most garnet grains are composed of Ti-bearing andradite-grossular.Often, garnet forms a core of the complex crystal, the outer part of which is represented by pyroxene of the diopside-esseneite series (Table 3).Fluorapatite is sporadically met in this rock; it forms skeletal crystals up to 90 µm in size.Within the ground mass of rock, gismondine-Ca and thomsonite-Ca occur in abundance.Gismondine-Ca forms veins in the space between calcite and opal up to 70 µm in thickness.Sometimes, the idiomorphic shape of gismondine-Ca crystals is visible.EPMA data for zeolites from the zeolite-bearing rock are given in Table 4.
Within the calcite veins, thomsonite-Ca and Sr-bearing thomsonite-Ca, clinoptilolite-Ca, and phillipsite-Ca are noted.Thomsonite-Ca forms idiomorphic crystals and splitting aggregates both in calcite veins and in the ground mass of rock.Aggregates of thomsonite-Ca reach more than 200 µm in size.Often, the internal part of the thomsonite-Ca crystal is enriched with Sr. Clinoptilolite-Ca forms radial-fibrous aggregates, the size of which do not exceed 100 µm.Clinoptilolite-Ca occurs only within calcite veins.Phillipsite-Ca is rather rare; it is presented by idiomorphic crystals of coarse-prismatic up to 80 µm in size.
Calcite is the main mineral of the studied zeolite rocks.Its content in the rock ranges from 30% to 40% (Table 2).It forms fine-grained aggregates and, as a rule, fills the space between both high-T minerals (pyroxene, fluorapatite, Ti-andradite) and later minerals such as zeolites and opal.Primary calcite did not undergo changes in low-temperature late processes.A former study remarked that occasionally, secondary calcite replaces zeolites, and pseudomorphs of calcite after zeolites are observed [7].Additionally, calcite forms veins with a thickness of 200 µm to 1-2 mm, and fills round voids 250-500 µm in size.

Raman Spectroscopy of the Main Rock-Forming Minerals and Zeolites
Calcite, fluorapatite, opal, minerals of the grossular-andradite series and diopsideesseneite series associated with the zeolite group minerals were studied with the help of Raman spectroscopy (Figure 5).In the Raman spectrum of calcite, the following bands were distinguished: 156 cm −1 , 283 cm −1 , 714 cm −1 , 1089 cm −1 , 1438 cm −1 , and 1751 cm −1 [28].The main bands in the Raman spectrum of fluorapatite are related to the symmetric stretching vibration mode of PO 4 3− at 965 cm −1 .Slightly marked bands at 890 cm −1 and 1009 cm −1 , referred to as vibration modes of SiO 4 4− and SO 4 2− , respectively, confirm an ellestadite type of substitution in the apatite-ellestadite series [29].The vibrations visible in the lower spectral values correspond to the bending vibration of the anions in the structure of fluorapatite.Domination of the fluorine member of apatite is confirmed by a characteristic Raman shift in the symmetric and asymmetric bending modes of the main functional group and asymmetric stretching vibrations of PO 4 3− [30].In the opal Raman spectrum, the most prominent strong wide band is visible between the 200 cm −1 and 500 cm −1 vibration region [31].The region between 3300 cm −1 and 3800 cm −1 is assigned to O-H bond stretching modes of the hydrous species incorporated in the silicate matrix [32].
Raman spectra of garnet group minerals belong to the grossular-andradite series.Presented spectra show three relatively intense modes around 369 cm −1 , 528 cm −1 , and 877 cm −1 , which can be assigned to rotational (R) (i.e., librational), internal bending, and stretching vibrations of the SiO 4 4− tetrahedra, respectively [33].Ca-clinopyroxenes presented in the studied rock belong to the diopside-esseneite series.Their Raman spectra are characterized by intense bends region with a maximum of 988 cm −1 for the Si-O nbr stretching mode and 667 cm −1 for Si-O br stretching bonds [34].A slight shift to lower values as well as changes in the spectrum in the region 750-850 cm −1 are probably due to the presence of Al in the tetrahedral positions of these members [34,35].In the 480-580 cm −1 region, bands assigned to the O-Si-O bending modes were observed, and in the lower region, bands were attributed to the cation-oxygen vibrations [34,36].Raman spectra were obtained for the next minerals of the zeolite group: thomsonite-Ca, Sr-bearing thomsonite-Ca, phillipsite-Ca, gismondine-Ca, and clinoptiolite-Ca (Figure 6).Raman spectra of the zeolite group minerals are classified according to the general types of the fundamental modes of the coupled TO 4 tetrahedra (T = Al or Si) and the H 2 O molecule.Furthermore, interpretation of the position of the ring bands depends on several factors: the number of ring members, Al:Si ratio, kind of non-tetrahedral cations, degree of ring deformation, degree of zeolite hydration, and arrangement of structure [37,38].
In the thomsonite-Ca Raman spectra, several strong and weak bands below 1100 cm −1 corresponding to the fundamental modes of (Al,Si)O 4 tetrahedra are distinguished.Strong bands in the range between 3000 and 3800 cm −1 caused by O-H stretching mode of water in crystal structure and a weak band at 1650 cm −1 are assigned to the bending mode of water [37].The presence of a very strong peak at 538 cm −1 is characteristic for thomsonite-Ca and scolecite within the natrolite group.Unambiguous identification between these two minerals can be easily performed considering the band region of the stretching vibration of the H 2 O molecules (3000-3600 cm −1 ).Thomsonite-Ca has a broad unresolved double peak, and scolecite has several sharp peaks in the water region [37].
Changes being results of substitution between Ca by Sr in the structure of thomsonite-Ca are visible in the lower wavenumbers below 535 cm −1 , which relates to the higher atomic mass of strontium and its larger ionic radius in comparison of calcium.Gismondine-Ca and phillipsite-Ca belong to the S4R group, where single four-membered rings are the basic structural elements [38]."Breathing" vibrations of the four-membered rings are predominant in the spectra of this zeolites group, and they are visible in the range of 470-520 cm −1 .Raman spectra of clinoptilolite belong to the most complicated SBU (Secondary Building Units) structure among all zeolites [39].This type of zeolites contains two groups of bands-one in the range 390-415 cm −1 , assigned to the five-membered ring vibrations, the other in the range 480-500 cm −1 , connected with four-membered ring vibrations [38].

Mechanical Properties of the Zeolite-Bearing Rock
The measured mechanical parameters of the zeolite-bearing rock are presented in Tables 5 and 6.According to the calculated values of porosity of the samples and their corresponding mechanical behavior, the rocks may be divided into two types: with porosity below 24% (between 18% and 24%) and porosity above 24% (between 24% and 27%).Zeolitebearing rocks are not completely homogeneous, and some samples contain amygdule-like pores.Thus, the high porosity of samples may be partly determined by the presence of amygdules.Relations between the point load index (I d ) and porosity (n) are presented in Figure 7.The latter demonstrates that when n < 24%, there is no correlation between I d and porosity (n): the squared regression coefficient is very small (R 2 = 0.0063).On the other hand, there is a pronounced influence of porosity (R 2 = 0.88) on the point load index (I d ) when n > 24%: I d decreases according to linear law with increasing porosity (n).The same trend was obtained in Figure 8, showing dependence between porosity and indirect (Brazilian) tensile strength (σ t ): n < 24% is not correlated with σ t (R 2 = 0.0329); the effect of porosity on σ t increases (R 2 = 0.75) when porosity n > 24%.Hence, two different levels of porosity (n < 24% and n > 24%) exhibit different effects on values of the point load index (I d ) and Brazilian tensile strength (σ t ).
The relationship between variable E and n for all samples shown in Table 6 is presented in Figure 9.It is clearly visible that the elastic modulus (E) increases according to logarithmic law (R 2 = 0.78 is reasonable) with decreasing porosity (n).The elastic modulus is a manifestation of rock stiffness, the length of grain to grain contacts, and the number of contacts per grain (textural features which directly influence rock stiffness; [40,41]).Thus, it must increase with decreasing void space.The elastic modulus is also partly dependent on mosaic texture, mineralogical composition, and pore types that influence on nature of con-tacts between grains in different rock types [42][43][44].It is likely because of the amygdaloidal texture of some samples that the correlation between E and n is not perfect (Figure 9).Since the porosity strongly influences the stiffness (elastic modulus E) of studied zeolite-bearing rocks, it is logical to suggest that it also influences rock strength (σ 1p ).Table 7 demonstrates the compressive strength of rock samples.n is calculated porosity (at ρ g = 2.5 g/cm 3 measured by helium porosimeter PH-220), σ 3 is confining pressure, σ 1p is peak axial stress, c is cohesion, and Φ is friction angle.
It is established that correlations between peak axial stress (σ 1p ) and confining pressure (σ 3 ) (R 2 = 0.85 and 0.94 for n < 24% and n > 24%, respectively) are linear, and, therefore, it is reasonable to use the Mohr failure criterion [45].
Figures 10 and 11 demonstrate the Mohr-Coulomb failure envelopes constructed for n < 24% and n > 24% rock porosities, respectively.The values of cohesion (c) and friction angle (Φ) defined by constructing tangents to the failure envelopes (in Figures 10 and 11) are shown in Table 7.It is obvious that an increase in the level of porosity (n) leads to a decrease in values of cohesion (c decreases from 4.96 to 4.7 MPa) and friction angle (Φ decreases from 44 • to 29.9 • ).Cohesion (c) is a measure of the inter-grain bonding strength.Lower cohesion means that grains have a lower tendency to clump or stick together.Since a higher porosity corresponds to a lower value of c, we may suggest that the high porosity (large void between grains) reduces the ability of grains of the studied zeolite to stick together.The angle of internal friction (Φ) shows how sample grains slide against each other.The higher the value of Φ, the greater the friction between the grains.Probably, the decrease in Φ with increasing n can be explained by the reduction of friction between grains due to an increase of void space between grains.The fact that the increase in porosity may lead to a decrease in friction angle is confirmed by [46][47][48] and [49] for some porous rocks and soils.

Discussion
Zeolite-bearing rocks are known in the Hatrurim Basin, and their position is mainly related to the tops of mountains in the northern part of the basin.Their location was determined by the marly protolith of the Taqiye Formation.According to the geological position of the zeolite-bearing rocks, it is claimed that their precursor was a pyrometamorphic rock of the olive unit.There are gradual contacts between two rock types.Supporting pieces of evidence are relics of high-temperature minerals belonging to the olive unit (pyroxene of diopside-esseneite composition, grossular-andradite garnet, fluorapatite, rare grains of plagioclase, and gehlenite) and geochemical correlation between the hornfels and the zeolite-bearing rocks.
Major minerals of the unit-pyroxene and plagioclase-were subjected to the zeolitization process.The necessary conditions of high alkalinity [50,51] were provided by the interaction of meteoric waters with other pyrometamorphic rock units of the Hatrurim Basin, whose mineralogical content resembles Portland cement [52].These are mainly spurrite, larnite, and gehlenite-bearing rocks.The contemporary flow of ultra-alkaline waters with pH up to 12.5 is evidenced in the Maqarin pyrometamorphic location, Jordan (Figure 1A) [53].The high alkalinity of the solution is provided by calcium and is related to the dissolution of Ca-bearing minerals.Geochemical comparison of protolith (anorthite-pyroxene hornfels) and zeolite-bearing rocks indicates enrichment of alteration products in Ca and Cr (Figure 3).The zeolitization process is fixing Ca [54].Cr shows high solubility in alkaline and ultra-alkaline solutions, a phenomenon which is also typical for the Hatrurim Complex [55].Consequently, water-rock interaction enriched and cemented zeolite-bearing rock by calcite and Cr-containing hydrous minerals.
A former study revealed that the most common zeolites are gismondine-Ca, thomsonite-Ca, and phillipsite-Ca.Additional zeolites that were identified in the "olive unit" are scolecite, mesolite, harmotome, and representatives of heulandite, harmotome, chabazite, and lévyne series [7].Gross also found epistilbite-encrusting amygdules in other rock types of the Mottled Zone.In the studied zeolite-bearing rocks, the major revealed zeolite minerals are gismondine-Ca, thomsonite-Ca, and phillipsite-Ca.Clinoptilolite-Ca is related to calcite veins.All zeolites chiefly contain calcium, characteristic of a siliceous-poor system [50].Phillipsite and clinoptilolite commonly occur in sedimentary rocks, whereas thomsonite-Ca, gismondine-Ca, and garronite-Ca are known to relate to hydrothermal origin [56].Some of the thomsonite-Ca grains are enriched in Sr. Preferential concentration of Sr was reported for natural zeolite minerals, including thomsonite [57].
The age of zeolitization is unknown.Several interglacial periods between 250 and 30 Ka or weathering during the wet period in the Levant between 6.3 and 3.3 Ka BP may be relevant to this process.In both cases, the zeolitic mantle persists for almost 5 Ka.
Zeolitic materials are utilized for construction uses and radioactive waste disposal.Hence, it was important to study the mechanical parameters of natural zeolite-bearing rocks that formed at least 5 Ka before.There are two different sets of mechanical parameters for porosity below and above 24%.Samples with n < 24% exhibit larger values of mechanical properties (peak axial stress, cohesion, friction angle, point load index, and Brazilian tensile strength) than samples with n > 24%.Values of the point load index (I d ), tensile (Brazilian) strength (σ t ), cohesion (c), and friction angle (Φ) obtained for all studied samples are 0.86-3.35MPa, 2-4.29 MPa, 4.7-4.96MPa, and 29.9-44 • , respectively.Elastic modulus (E) ranges from 5.36 MPa to 15.25 MPa, and Poisson's ratio (v) is between 0.11 and 0.21.
Summing up, the obtained chemical-mineralogical results of the zeolite-bearing rocks make them similar to carbonated zeolite-blended Portland mortar.The analogy between the Hatrurim pyrometamorphic rocks and concretes and cement was made previously.The mineralogy and composition of high-temperature spurrite-, gehlenite-and larnite-bearing marbles are similar to that of the Portland cement and belite (the synthetic counterpart of larnite) sulfoaluminate cement [52, [68][69][70].The products of their low-temperature alteration are similar to carbonated Portland mortars [52,69].Products of low-temperature alteration of gehlenite-bearing marbles, katoite-bearing rocks, also resemble belite sulfoaluminate mortar [70].
Natural zeolite-bearing rocks of the Hatrurim Basin are stable for corrosion in the desert climate of the Judean Mountains for at least 5 Ka.The zeolite-bearing blocks sampled at the surface show mechanical characteristics comparable to zeolite-blended mortar.

Figure 1 .
Figure 1.Geographical position of the study area.(A)-Outcrops of the Hatrurim Complex in Israel and Jordan; (B)-general schematic stratigraphic position of the Hatrurim Complex in the Late Cretaceous-Paleogene sequence of Israel [7,10]; (C)-the outcrops of the "olive unit" in the Hatrurim Basin [11].The schematic locality of Mt.Ye'elim is shown; (D)-brecciated cliff of fresh anorthite-pyroxene hornfels, the "olive unit".(E)-Zeolite-bearing rock with typical zonal barite concretions.The size of coin is 2.25 cm.

Figure 2 .
Figure 2. The Hatrurim Basin, Mt.Ye'elim, eastern slope composed of pyrometamorphic rocks and products of their alteration.Relative height of Mt.Ye'elim is about 80 m.Ordinary sedimentary rocks are seen in the background.

Figure 3 .
Figure 3. Isocon diagram of the zeolite-bearing rock vs. hornfels of the olive unit.

Figure 5 .
Figure 5. Raman spectrum of major mineral phases in the zeolite-bearing rock.Raman spectra of opal are represented in two figures within the range 0-1800 (A) and 3200-3800 cm −1 (B).

Figure 7 .
Figure 7. Relations between point load index (I d ) and two different level of porosity (n < 24% and n > 24%) for the zeolite-bearing rocks.

Figure 9 .
Figure 9.The relation between elastic modulus (E) and porosity (n) of the zeolite-bearing rocks.

Figure 10 .
Figure 10.Mohr-Coulomb failure envelopes in terms of normal and shear stress for porosity of the zeolite-bearing rock n < 24%.The tangent line is composed according to best fit between σ 1p and σ 3. Determined parameters are c = 4.96 MPa and Φ = 44 • .

Figure 11 .
Figure 11.Mohr-Coulomb failure envelopes in terms of normal and shear stress for porosity of the zeolite-bearing rock n > 24%.Determined parameters are c = 4.7 MPa and Φ = 29.9• .
Author Contributions: Conceptualization: Y.V. and V.P.; data curation, methodology, resources, software, investigation, visualization, writing, and editing: Ł.K., V.P., Y.V., K.N., K.B. and I.G.; supervision: Y.V.; funding acquisition: I.G.All authors have read and agreed to the published version of the manuscript.Funding: This research was partially supported by research project No. UMO-2013/11/B/ST10/00272 of the National Science Centre of Poland.Data Availability Statement: Data are not subject to access restrictions.

Table 2 .
Main minerals of the zeolite-bearing rocks and their volumes (wt.%).

Table 3 .
Chemical composition of pyroxene and garnets from the zeolite-bearing rocks.

Table 4 .
Results of chemical analyses of zeolites from the zeolite-bearing rocks.
1-Below the detection limit; 2 -calculated on the basis of stoichiometry; 3 -atoms per formula unit.

Table 5 .
Point load index (I d ) and indirect (Brazilian) tensile strength (σ t ) of the zeolite-bearing rocks.
n is calculated porosity (at grain density of p g = 2.5 g/cm3measured by helium porosimeter PH-220), I d is point load strength, σ t is indirect tensile (Brazilian) strength.

Table 6 .
Results of the compressive tests conducted on the zeolite-bearing rocks.

Table 7 .
Compressive strength of the zeolite-bearing rocks.