curiosity at gale crater mars characterization and analysis of the rocknest sand shadow the rocknest aeolian deposit is similar to aeolian features analyzed by the mars exploration rovers mers spirit and opportunity the fraction of sand 150 micrometers in size contains 55 crystalline material consistent with a basaltic heritage and 45 x ray amorphous material the amorphous component of rocknest is iron rich and silicon poor and is the host of the volatiles water oxygen sulfur dioxide carbon dioxide and chlorine detected by the sample analysis at mars instrument and of the fine grained nanophase oxide component first described from basaltic soils analyzed by mers the similarity between soils and aeolian materials analyzed at gusev crater meridiani planum and gale crater implies locally sourced globally similar basaltic materials or globally and regionally sourced basaltic components deposited locally at all three locations

chemistry and mineralogy of outcrops at meridiani planum analyses of outcrops created by the impact craters endurance fram and eagle reveal the broad lateral continuity of chemical sediments at the meridiani planum exploration site on mars approximately ten mineralogical components are implied in these salt rich silicic sediments from measurements by instruments on the opportunity rover compositional trends in an apparently intact vertical stratigraphic sequence at the karatepe west ingress point at endurance crater are consistent with non uniform deposition or with subsequent migration of mobile salt components dominated by sulfates of magnesium striking variations in cl and enrichments of br combined with diversity in sulfate species provide further evidence of episodes during which temperatures ph and water to rock ratios underwent significant change to first order the sedimentary sequence examined to date is consistent with a uniform reference composition modified by movement of major sulfates upward and of minor chlorides downward this reference composition has similarities to martian soils supplemented by sulfate anion and the alteration products of mafic igneous minerals lesser cementation in lower stratigraphic units is reflected in decreased energies for grinding with the rock abrasion tool survival of soluble salts in exposed outcrop is most easily explained by absence of episodes of liquid h2o in this region since the time of crater formation

rb sr and sm nd isotopic and ree studies of igneous components in the bulk matrix domain of martian breccia northwest africa 7034 the bulk matrix domain of the martian breccia nwa 7034 was examined petrographically and isotopically to better understand the provenance and age of the source material that make up the breccia both 147sm 143nd and 146sm 142nd age results for mineral separates from the bulk matrix portion of breccia nwa 7034 suggest that various lithological components in the breccia probably formed contemporaneously 4 44 ga ago this old age is in excellent agreement with the upper intersection ages 4 35 4 45 ga for u pb discordia and also concordia defined by zircon and baddeleyite grains in matrix and igneous textured clasts consequently we confirm an ancient age for the igneous components that make up the nwa 7034 breccia substantial disturbance in the rb sr system was detected and no age significance could be gleaned from our rb sr data the disturbance to the rb sr system may be due to a thermal event recorded by bulk rock k ar ages of 1 56 ga and u pb ages of phosphates at about 1 35 1 5 ga which suggest partial resetting from an unknown thermal event s possibly accompanying breccia formation the nwa 7034 bulk rock is lree enriched and similar to kreep rich lunar rocks which indicates that the earliest martian crust was geochemically enriched this enrichment supports the idea that the crust is one of the enriched geochemical reservoirs on mars that have been detected in studies of other martian meteorites

constraints on the depth and thermal vigor of melting in the martian mantle studies of rocks in gale crater and clasts within the martian meteorite breccia northwest africa nwa 7034 and paired stones have expanded our knowledge of the diversity of igneous rocks that make up the martian crust beyond those compositions exhibited in the meteorite collection or analyzed at any other landing site therefore the magmas that gave rise to these rocks may have been generated at significantly different conditions in the martian mantle than those derived from previously studied rocks here we build upon our previous models of basalt formation based on rocks analyzed in gusev crater and meridiani planum to the new models of basalt formation for compositions from gale crater and a clast in meteorite nwa 7034 estimates for the mantle potential temperature tp based on noachian age rock analyses in gale crater gusev crater and bounce rock in meridiani planum and a vitrophyre clast in nwa 7034 are within error which suggests that the calculated average tp of 1450 70 c may represent an average global mantle temperature during the noachian the tp estimates for the hesperian and amazonian based on orbital analyses of the chemistry of the crust are lower in temperature than our estimates for the noachian which is consistent with simple convective cooling of the interior of mars however the tp estimates from the young meteorites are significantly higher than the estimates based on surface chemistry and are consistent with localized hot spot melting and not heating up of the interior

ferrian saponite from the santa monica mountains california u s a earth characterization as an analog for clay minerals on mars with application to yellowknife bay in gale crater ferrian saponite from the eastern santa monica mountain near griffith park los angeles california was investigated as a mineralogical analog to smectites discovered on mars by the chemin x ray diffraction instrument onboard the mars science laboratory msl rover the martian clay minerals occur in sediment of basaltic composition and have 02 l diffraction bands peaking at 4 59 a consistent with tri octahedral smectites the griffith saponite occurs in basalts as pseudomorphs after olivine and mesostasis glass and as fillings of vesicles and cracks and has 02 l diffraction bands at that same position we obtained chemical compositions by electron microprobe x ray diffraction patterns with a lab version of the chemin instrument mossbauer spectra and visible and near ir reflectance vnir spectra on several samples from that locality the griffith saponite is magnesian mg mg fe 65 70 lacks tetrahedral fe 3 and octahedral al 3 and has fe 3 fe from 64 to 93 its chemical composition is consistent with a fully tri octahedral smectite but the abundance of fe 3 gives a nominal excess charge of 1 to 2 per formula unit the excess charge is likely compensated by substitution of o 2 for oh causing distortion of octahedral sites as inferred from mossbauer spectra we hypothesize that the griffith saponite was initially deposited with all its iron as fe 2 and was oxidized later x ray diffraction shows a sharp 001 peak at 15 a 00 l peaks and a 02 l diffraction band at the same position 4 59 a and shape as those of the martian samples indicating that the martian saponite is not fully oxidized vnir spectra of the griffith saponite show distinct absorptions at 1 40 1 90 2 30 2 32 and 2 40 m arising from h 2 o and hydroxyl groups in various settings the position of the 2 31 m spectral feature varies systematically with the redox state of the octahedrally coordinated fe this correlation may permit surface oxidation state to be inferred in some cases from vnir spectra of mars obtained from orbit and in any case ferrian saponite is a viable assignment for spectral detections in the range 2 30 2 32 m

formation of jarosite bearing deposits through aqueous oxidation of pyrite at meridiani planum mars 1 the discovery of sulfate rich layered deposits with hematite spherules at the landing site of the opportunity rover is consistent with mineral deposition in an aqueous environment we evaluate conditions responsible for the formation of a jarosite goethite gypsum assemblage with speciation calculations the results show that the assemblage could have precipitated from acidic solutions formed through near surface aqueous oxidation of pyrite our hypothesis is that regional heating in the meridiani planum caused a release of sulfide rich hydrothermal waters leading to formation of pyrite rich regional deposits in a depression aqueous oxidation of these deposits by atmospheric o2 created an acidic environment that allowed formation of sulfates and goethite partial neutralization of the solution caused further goethite precipitation and conversion of jarosite to goethite leading to formation of goethite concretions subsequent dehydration of goethite to coarse grained hematite would also have been facilitated by regional heating

iron mineralogy and aqueous alteration from husband hill through home plate at gusev crater mars results from the mossbauer instrument on the spirit mars exploration rover 1 spirit s mossbauer mb instrument determined the fe mineralogy and oxidation state of 71 rocks and 43 soils during its exploration of the gusev plains and the columbia hills west spur husband hill haskin ridge northern inner basin and home plate on mars the plains are predominantly float rocks and soil derived from olivine basalts outcrops at west spur and on husband hill have experienced pervasive aqueous alteration as indicated by the presence of goethite olivine rich outcrops in a possible mafic ultramafic horizon are present on haskin ridge relatively unaltered basalt and olivine basalt float rocks occur at isolated locations throughout the columbia hills basalt and olivine basalt outcrops are found at and near home plate a putative hydrovolcanic structure at least three pyroxene compositions are indicated by mb data mb spectra of outcrops barnhill and torquas resemble palagonitic material and thus possible supergene aqueous alteration deposits of fe3 sulfate soil located at paso robles arad and tyrone are likely products of acid sulfate fumarolic and or hydrothermal activity possibly in connection with home plate volcanism hematite rich outcrops between home plate and tyrone e g montalva may also be products of this aqueous activity low water to rock ratios isochemical alteration are implied during palagonite goethite and hematite formation because bulk chemical compositions are basaltic so3 free basis high water to rock ratios leaching under acid sulfate conditions are implied for the high sio2 rock and soil in eastern valley and the float rock fuzzysmith which has possible pyrite marcasite as a hydrothermal alteration product

the origin and implications of clay minerals from yellowknife bay gale crater mars the mars science laboratory msl rover curiosity has documented a section of fluvio lacustrine strata at yellowknife bay ykb an embayment on the floor of gale crater approximately 500 m east of the bradbury landing site x ray diffraction xrd data and evolved gas analysis ega data from the chemin and sam instruments show that two powdered mudstone samples named john klein and cumberland drilled from the sheepbed member of this succession contain up to 20 wt clay minerals a trioctahedral smectite likely a ferrian saponite is the only clay mineral phase detected in these samples smectites of the two samples exhibit different 001 spacing under the low partial pressures of h2o inside the chemin instrument relative humidity 1 smectite interlayers in john klein collapsed sometime between clay mineral formation and the time of analysis to a basal spacing of 10 a but largely remain open in the cumberland sample with a basal spacing of 13 2 a partial intercalation of cumberland smectites by metal hydroxyl groups a common process in certain pedogenic and lacustrine settings on earth is our favored explanation for these differences the relatively low abundances of olivine and enriched levels of magnetite in the sheepbed mudstone when compared with regional basalt compositions derived from orbital data suggest that clay minerals formed with magnetite in situ via aqueous alteration of olivine mass balance calculations are permissive of such a reaction moreover the sheepbed mudstone mineral assemblage is consistent with minimal inputs of detrital clay minerals from the crater walls and rim early diagenetic fabrics suggest clay mineral formation prior to lithification thermodynamic modeling indicates that the production of authigenic magnetite and saponite at surficial temperatures requires a moderate supply of oxidants allowing circum neutral ph the kinetics of olivine alteration suggest the presence of fluids for thousands to hundreds of thousands of years mineralogical evidence of the persistence of benign aqueous conditions at ykb for extended periods indicates a potentially habitable environment where life could establish itself mediated oxidation of fe 2 in olivine to fe 3 in mag

mineralogy of an ancient lacustrine mudstone succession from the murray formation gale crater mars the mars science laboratory curiosity rover has been traversing strata at the base of aeolis mons informally known as mount sharp since september 2014 the murray formation makes up the lowest exposed strata of the mount sharp group and is composed primarily of finely laminated lacustrine mudstone intercalated with rare crossbedded sandstone that is prodeltaic or fluvial in origin we report on the first three drilled samples from the murray formation measured in the pahrump hills section rietveld refinements and fullpat full pattern fitting analyses of x ray diffraction patterns measured by the msl chemin instrument provide mineral abundances refined unit cell parameters for major phases giving crystal chemistry and abundances of x ray amorphous materials our results from the samples measured at the pahrump hills and previously published results on the buckskin sample measured from the marias pass section stratigraphically above pahrump hills show stratigraphic variations in the mineralogy phyllosilicates hematite jarosite and pyroxene are most abundant at the base of the pahrump hills and crystalline and amorphous silica and magnetite become prevalent higher in the succession some trace element abundances measured by apxs also show stratigraphic trends zn and ni are highly enriched with respect to average mars crust at the base of the pahrump hills by 7 7 and 3 7 times respectively and gradually decrease in abundance in stratigraphically higher regions near marias pass where they are depleted with respect to average mars crust by more than an order of magnitude in some targets the mn stratigraphic trend is analogous to zn and ni however mn abundances are close to those of average mars crust at the base of pahrump hills rather than being enriched and mn becomes increasingly depleted moving upsection minerals at the base of the pahrump hills in particular jarosite and hematite as well as enrichments in zn ni and mn are products of acid sulfate alteration on earth we hypothesize that multiple influxes of mildly to moderately acidic pore fluids resulted in diagenesis of the murray formation and the observed mineralogical and geochemical variations the preservation of some minerals that are highly susceptible to dissolution at low ph e g mafic minerals and fluorapatite suggests that acidic events were not long lived and that fluids may not have been extremely acidic ph 2ph 2 alternatively the observed mineralogical variations within the succession may be explained by deposition in lake waters with variable eh and or ph where the lowermost sediments were deposited in an oxidizing perhaps acidic lake setting and sediments deposited in the upper pahrump hills and marias pass were deposited lake waters with lower eh and higher ph

the potassic sedimentary rocks in gale crater mars as seen by chemcam on board curiosity key points mean k2o abundance in sedimentary rocks 5 times higher than that of the average martian crust presence of alkali feldspars and k phyllosilicates in basaltic sedimentary rocks along the traverse the k bearing minerals likely have a detrital origin

mineralogy provenance and diagenesis of a potassic basaltic sandstone on mars chemin x ray diffraction of the windjana sample kimberley area gale crater the windjana drill sample a sandstone of the dillinger member kimberley formation gale crater mars was analyzed by chemin x ray diffraction xrd in the msl curiosity rover from rietveld refinements of its xrd pattern windjana contains the following sanidine 21 weight or95 augite 20 magnetite 12 pigeonite olivine plagioclase amorphous and smectitic material 25 and percent levels of others including ilmenite fluorapatite and bassanite from mass balance on the alpha proton x ray spectrometer apxs chemical analysis the amorphous material is fe rich with nearly no other cations like ferrihydrite the windjana sample shows little alteration and was likely cemented by its magnetite and ferrihydrite from chemcam laser induced breakdown spectrometer libs chemical analyses windjana is representative of the dillinger and mount remarkable members of the kimberley formation libs data suggest that the kimberley sediments include at least three chemical components the most k rich targets have 5 6 k2o 1 8 times that of windjana implying a sediment component with 40 sanidine e g a trachyte a second component is rich in mafic minerals with little feldspar like a shergottite a third component is richer in plagioclase and in na2o and is likely to be basaltic the k rich sediment component is consistent with apxs and chemcam observations of k rich rocks elsewhere in gale crater the source of this sediment component was likely volcanic the presence of sediment from many igneous sources in concert with curiosity s identifications of other igneous materials e g mugearite implies that the northern rim of gale crater exposes a diverse igneous complex at least as diverse as that found in similar age terranes on earth

jarosite and hematite at meridiani planum from opportunity s mossbauer spectrometer mossbauer spectra measured by the opportunity rover revealed four mineralogical components in meridiani planum at eagle crater jarosite and hematite rich outcrop hematite rich soil olivine bearing basaltic soil and a pyroxene bearing basaltic rock bounce rock spherules interpreted to be concretions are hematite rich and dispersed throughout the outcrop hematitic soils both within and outside eagle crater are dominated by spherules and their fragments olivine bearing basaltic soil is present throughout the region bounce rock is probably an impact erratic because jarosite is a hydroxide sulfate mineral its presence at meridiani planum is mineralogical evidence for aqueous processes on mars probably under acid sulfate conditions

a habitable fluvio lacustrine environment at yellowknife bay gale crater mars the curiosity rover discovered fine grained sedimentary rocks which are inferred to represent an ancient lake and preserve evidence of an environment that would have been suited to support a martian biosphere founded on chemolithoautotrophy this aqueous environment was characterized by neutral ph low salinity and variable redox states of both iron and sulfur species carbon hydrogen oxygen sulfur nitrogen and phosphorus were measured directly as key biogenic elements by inference phosphorus is assumed to have been available the environment probably had a minimum duration of hundreds to tens of thousands of years these results highlight the biological viability of fluvial lacustrine environments in the post noachian history of mars

silicate mineralogy of martian meteorites abstract basalts and basaltic cumulates from mars delivered to earth as meteorites carry a record of the history of that planet from accretion to initial differentiation and subsequent volcanism up to recent times we provide new microprobe data for plagioclase olivine and pyroxene from 19 of the martian meteorites that are representative of the six types of martian rocks we also provide a comprehensive wds map dataset for each sample studied collected at a common magnification for easy comparison of composition and texture the silicate data shows that plagioclase from each of the rock types shares similar trends in ca na k and that k2o na2o wt of plagioclase multiplied by the al content of the bulk rock can be used to determine whether a rock is enriched or depleted in nature olivine data show that meteorite y 980459 is a primitive melt from the martian mantle as its olivine crystals are in equilibrium with its bulk rock composition all other olivine bearing shergottites have been affected by fractional crystallization pyroxene quadrilateral compositions can be used to isolate the type of melt from which the grains crystallized and minor element concentrations in pyroxene can lend insight into parent melt compositions in a comparative planetary mineralogy context plagioclase from mars is richer in na than terrestrial and lunar plagioclase the two most important factors contributing to this are the low activity of al in martian melts and the resulting delayed nucleation of plagioclase in the crystallizing rock olivine from martian rocks shows distinct trends in ni co and cr systematics compared with olivine from earth and moon the trends are due to several factors including oxygen fugacity melt compositions and melt structures properties which show variability among the planets finally fe mn ratios in both olivine and pyroxene can be used as a fingerprint of planetary parentage where minerals show distinct planetary trends that may have been set at the time of planetary accretion although the silicate mineralogical data alone cannot support one specific model of martian magmatism over another the data does support the basic igneous reservoirs proposed for mars and may also be used to constrain some aspects of specific petrogenetic models examples include enriched and depleted reservoirs that can be identified by plagioclase k na and al composition multivalent element partitioning in olivine and pyroxene v cr elucidates oxygen fugacity conditions of the reservoirs and minor element concentrations i e cr in pyx show that proposed fractional crystallization models linking y 980459 to que 94201 will not work

constraints on abundance composition and nature of x ray amorphous components of soils and rocks at gale crater mars x ray diffraction patterns of the three samples analyzed by curiosity s chemistry and mineralogy chemin instrument during the first year of the mars science laboratory mission the rocknest sand and the john klein and cumberland drill fines both extracted from the sheepbed mudstone show evidence for a significant amorphous component of unclear origin we developed a mass balance calculation program that determines the range of possible chemical compositions of the crystalline and amorphous components of these samples within the uncertainties of mineral abundances derived from chemin data in turn the chemistry constrains the minimum abundance of amorphous component required to have realistic compositions all oxides 0 wt 21 22 wt for rocknest and 15 20 wt for cumberland in good agreement with estimates derived from the diffraction patterns 27 and 31 wt respectively despite obvious differences between the rocknest sand and the sheepbed mudstone the amorphous components of the two sites are chemically very similar having comparable concentrations of sio2 tio2 al2o3 cr2o3 feot cao na2o k2o and p2o5 mgo tends to be lower in rocknest although it may also be comparable between the two samples depending on the exact composition of the smectite in sheepbed the only unambiguous difference is the so3 content which is always higher in rocknest the observed similarity suggests that the two amorphous components share a common origin or formation process the individual phases possibly present within the amorphous components include volcanic or impact glass hisingerite or silica ferrihydrite amorphous sulfates or adsorbed so42 and nanophase ferric oxides

mossbauer mineralogy of rock soil and dust at meridiani planum mars opportunity s journey across sulfate rich outcrop basaltic sand and dust and hematite lag deposits additonal co authors p gutlich e kankeleit t mccoy dw mittlefehldt f renz me schmidt b zubkov sw squyres re arvidson

hydrothermal synthesis of hematite spherules and jarosite implications for diagenesis and hematite spherule formation in sulfate outcrops at meridiani planum mars we synthesized hematite spherules whose mineralogic chemical and crystallographic properties are strikingly similar to those for the hematite rich spherules in lag deposits on the surface and embedded in outcrops at meridiani planum mars the spherules were synthesized in the laboratory along with hydronium jarosite and minor hydronium alunite from fe al mg s cl acid sulfate solutions under hydrothermal conditions the reaction sequence was 1 precipitation of hydronium jarosite 2 jarosite dissolution and precipitation of hematite spherules and 3 precipitation of hydronium alunite upon depletion of hydronium jarosite the spherules exhibit a radial growth texture with the crystallographic c axis aligned along the radial direction so that thermal emission spectra have no hematite emissivity minimum at 390 cm 1 our experiments show that hydrothermal acid sulfate solutions are a pathway for formation of jarosite and the hematite spherules at meridiani planum mars

naturally occurring ferric iron sanidine from the leucite hills lamproite sanidine crystals precipitating from lamproitic magmas characteristically contain appreciable amounts of feh sanidine grains from the leucite hills lamproites wyoming have compositions in which up to 70 mol of the kaisi30gmolecule is replaced by kfehsi30g thus constituting a new natural feldspar component sanidine is among the last phases to crystallize in the groundmass of leucite hills lamproites and rarely exceeds 150 lmin length nearly all grains are zoned in fe ranging from 2 5 wt fez03in the cores to 19 6 wt fez03at rims adjacent to quenched glass the fe rich rims are relatively narrow on 010 crystal faces in comparison with 001 faces maximum width 10 lm probably reflecting faster 001 and slower growing 010 crystallographic directions a near perfect correlation is obtained by combining ti mg and excess si cations with feh in tetrahedral substitution for ai insufficient numbers of r2 cations exist to balance the high concentrations of mg through an r2 mg2 r r substitution suggestingthe exchangemg2 si4 ai i in 2kalsi30g analogousto that found in synthetic leucite and kalsilite selected area electron diffraction and convergent beam electron diffraction show that the fe rich sanidine rims have a c2 m structure with cell dimensions of a 8 68 t 0 15 b 13 14 t 0 23 c 7 31 t 0 15 a ex 90 0 t 0 54 j 116 0 t 0 46 y 90 0 t 0 33 and a calculated cell volume of 747 t 21 a3 these crystallographic data are in very close agreement to those obtained previously for synthetic kfehsi30g the unusually high concentrations of feh ti and mg in the sanidine rims are likely the consequence of rapid crystallization during quenching of an unusually siand k rich yet ai deficient residual magma

petrography and composition of martian regolith breccia meteorite northwest africa 7475 the northwest africa nwa 7475 meteorite is one of the several stones of paired regolith breccias from mars based on petrography oxygen isotope mineral compositions and bulk rock compositions its inventory of lithic clasts is dominated by vitrophyre impact melts that were emplaced while they were still molten other clast types include crystallized impact melt rocks evolved plutonic rocks possible basalts contact metamorphosed rocks and siltstones impact spherules and vitrophyre shards record airborne transport and accreted dust rims were sintered on most clasts presumably during residence in an ejecta plume the clast assemblage records at least three impact events one that formed an impact melt sheet on mars 4 4 ga ago a second that assembled nwa 7475 from impactites associated with the impact melt sheet at 1 7 1 4 ga and a third that launched nwa 7475 from mars 5 ma ago mildly shocked pyroxene and plagioclase constrain shock metamorphic conditions during launch to 5 and 15 gpa the mild postshock heating that resulted from these shock pressures would have been insufficient to sterilize this water bearing lithology during launch magnetite maghemite and pyrite are likely products of secondary alteration on mars textural relationships suggest that calcium carbonate and goethite are probably of terrestrial origin yet trace element chemistry indicates relatively low terrestrial alteration comparison of mars odyssey gamma ray spectrometer data with the fe and th abundances of nwa 7475 points to a provenance in the ancient southern highlands of mars gratteri crater with an age of 5 ma and an apparent diameter of 6 9 km marks one possible launch site of nwa 7475

the upper atmospheres of uranus and neptune we review the current understanding of the upper atmospheres of uranus and neptune and explore the upcoming opportunities available to study these exciting planets the ice giants are the least un

mineralogy at meridiani planum from the mini tes experiment on the opportunity rover the miniature thermal emission spectrometer mini tes on opportunity investigated the mineral abundances and compositions of outcrops rocks and soils at meridiani planum coarse crystalline hematite and olivine rich basaltic sands were observed as predicted from orbital tes spectroscopy outcrops of aqueous origin are composed of 15 to 35 by volume magnesium and calcium sulfates a high silica component modeled as a combination of glass feldspar and sheet silicates 20 to 30 and hematite only minor jarosite is identified in mini tes spectra mini tes spectra show only a hematite signature in the millimeter sized spherules basaltic materials have more plagioclase than pyroxene contain olivine and are similar in inferred mineral composition to basalt mapped from orbit bounce rock is dominated by clinopyroxene and is close in inferred mineral composition to the basaltic martian meteorites bright wind streak material matches global dust waterlain rocks covered by unaltered basaltic sands suggest a change from an aqueous environment to one dominated by physical weathering

silicic volcanism on mars evidenced by tridymite in high sio2 sedimentary rock at gale crater tridymite a low pressure high temperature 870 c sio2 polymorph was detected in a drill sample of laminated mudstone buckskin at marias pass in gale crater mars by the chemistry and mineralogy x ray diffraction instrument onboard the mars science laboratory rover curiosity the tridymitic mudstone has 40 wt crystalline and 60 wt x ray amorphous material and a bulk composition with 74 wt sio2 alpha particle x ray spectrometer analysis plagioclase 17 wt of bulk sample tridymite 14 wt sanidine 3 wt cation deficient magnetite 3 wt cristobalite 2 wt and anhydrite 1 wt are the mudstone crystalline minerals amorphous material is silica rich 39 wt opal a and or high sio2 glass and opal ct volatile bearing 16 wt mixed cation sulfates phosphates and chlorides perchlorates chlorates and has minor tio2 and fe2o3t oxides 5 wt rietveld refinement yielded a monoclinic structural model for a well crystalline tridymite consistent with high formation temperatures terrestrial tridymite is commonly associated with silicic volcanism and detritus from such volcanism in a lake gale catchment environment can account for buckskin s tridymite cristobalite feldspar and any residual high sio2 glass these cogenetic detrital phases are possibly sourced from the gale crater wall rim central peak opaline silica could form during diagenesis from high sio2 glass as amorphous precipitated silica or as a residue of acidic leaching in the sediment source region or at marias pass the amorphous mixed cation salts and oxides and possibly the crystalline magnetite otherwise detrital are primary precipitates and or their diagenesis products derived from multiple infiltrations of aqueous solutions having variable compositions temperatures and acidities anhydrite is post lithification fracture vein fill

mineralogy of a mudstone at yellowknife bay gale crater mars sedimentary rocks at yellowknife bay gale crater on mars include mudstone sampled by the curiosity rover the samples john klein and cumberland contain detrital basaltic minerals calcium sulfates iron oxide or hydroxides iron sulfides amorphous material and trioctahedral smectites the john klein smectite has basal spacing of similar to 10 angstroms indicating little interlayer hydration the cumberland smectite has basal spacing at both similar to 13 2 and similar to 10 angstroms the larger spacing suggests a partially chloritized interlayer or interlayer magnesium or calcium facilitating h2o retention basaltic minerals in the mudstone are similar to those in nearby eolian deposits however the mudstone has far less fe forsterite possibly lost with formation of smectite plus magnetite late noachian early hesperian or younger age indicates that clay mineral formation on mars extended beyond noachian time

multiple stages of aqueous alteration along fractures in mudstone and sandstone strata in gale crater mars the mars rover curiosity in gale crater conducted the first ever direct chemical and mineralogical comparisons of samples that have clear parent unaltered and daughter altered relationships the mineralogy and chemistry of samples within and adjacent to alteration halos in a sandstone formation were established by the chemistry and mineralogy chemin x ray diffraction xrd instrument and the alpha particle x ray spectrometer apxs respectively the stimson formation sandstones unconformably overlie the murray mudstone formation and represent the youngest stratigraphic unit explored by curiosity to date aqueous alteration of the parent sandstone resulted in a loss of half of the original crystalline mineral phases and a three fold increase in x ray amorphous material aqueous fluids extensively leached mg al mn fe ni zn and other elements from the parent material decreased the pyroxene to feldspar ratio by a factor of two introduced ca and mixed cation sulfates and both passively and actively enriched the silica content leaching of mg al mn fe ni and zn and enrichment of si and s are also observed in alteration halos in the underlying mudstone these observations are consistent with infiltration of subsurface fluids initially acidic and then alkaline propagating along fractures crosscutting the stimson sandstone and murray mudstone the geochemistry and mineralogy suggest a complicated diagenetic history with multiple stages of aqueous alteration under a variety of environmental conditions e g both low and moderate ph the formation of these alteration halos post dates lithification of the sandstones and mudstones and represents one of the youngest hydrogeologic events presently known to have occurred in gale crater

accurate analytic representations of solar time and seasons on mars with applications to the pathfinder surveyor missions efficient analytic recipes are presented for a moderately accurate closed form calculation of the areocentric longitude ls analemmic equation of time and solar hour angles on mars along with an approximate recovery of the viking local lander time the adopted fit to the fictitious mean sun implies a mars tropical orbit period of 686 9725d

regolith breccia northwest africa 7533 mineralogy and petrology with implications for early mars northwest africa 7533 a polymict martian breccia consists of fine grained clast laden melt particles and microcrystalline matrix while both melt and matrix contain medium grained noritic monzonitic material and crystal clasts the matrix also contains lithic clasts with zoned pigeonite and augite plus two feldspars microbasaltic clasts vitrophyric and microcrystalline spherules and shards the clast laden melt rocks contain clump like aggregates of orthopyroxene surrounded by aureoles of plagioclase some shards of vesicular melt rocks resemble the pyroxene plagioclase clump aureole structures submicron size matrix grains show some triple junctions but most are irregular with high intergranular porosity the noritic monzonitic rocks contain exsolved pyroxenes and perthitic intergrowths and cooled more slowly than rocks with zoned pyroxene or fine grain size noritic material contains orthopyroxene or inverted pigeonite augite calcic to intermediate plagioclase and chromite to cr bearing magnetite monzonitic clasts contain augite sodic plagioclase k feldspar ti bearing magnetite ilmenite chlorapatite and zircon these feldspathic rocks show similarities to some rocks at gale crater like black trout mara and jake m the most magnesian orthopyroxene clasts are close to alh 84001 orthopyroxene in composition all these materials are enriched in siderophile elements indicating impact melting and incorporation of a projectile component except for ni poor pyroxene clasts which are from pristine rocks clast laden melt rocks spherules shards and siderophile element contents indicate formation of nwa 7533 as a regolith breccia the zircons mainly derived from monzonitic melt rocks crystallized at 4 43 0 03 ga humayun et al 2013 and a 147sm 143nd isochron for nwa 7034 yielding 4 42 0 07 ga nyquist et al 2016 defines the crystallization age of all its igneous portions the zircon from the monzonitic rocks has a higher 17o than other martian meteorites explained in part by assimilation of regolith materials enriched during surface alteration nemchin et al 2014 this record of protolith interaction with atmosphere hydrosphere during regolith formation before melting demonstrates a thin atmosphere a wet early surface environment on mars and an evolved crust likely to have contaminated younger extrusive rocks the latest events recorded when the breccia was on mars are resetting of apatite much feldspar and some zircons at 1 35 1 4 ga bellucci et al 2015 and formation of ni bearing pyrite veins during or shortly after this disturbance lorand et al 2015

looking for jarosite on mars the low temperature crystal structure of jarosite single crystal diffraction of jarosite kfe 3 3 so 4 2 oh 6 has been undertaken at low temperatures that proxy for martian surface conditions room temperature data are consistent with literature data a 7 2913 5 c 17 1744 17 and v 790 72 11 in r 3 m while the first low temperature data for the mineral is presented at 253 213 173 and 133 k data collections between 297 and 133 k show strongly anisotropic thermal expansion with the c axis much more expandable than the a axis much of the anisotropy is due to strong distortion of the ko 12 polyhedron which increases by 8 between 297 and 133 k the data sets can aid in the identification of jarosite by x ray diffraction of martian soils using the curiosity rover s chemin instrument