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A natural grossular garnet was found to have a luminescence spectrum with a narrow vibrational structure and short decay time that is unusual for minerals. We propose that such emission is generated by Mn²⁺ accompanied by defect F-centers which both enhance the transition probability and give rise to sensitivity to optical bleaching and reconstitution via irradiation. The elevated Mn concentration in comparison with other potential luminescent impurities was confirmed by LIBS analysis. Such interpretation contradicts the traditional opinion that Mn²⁺ centers in minerals are characterized only by broadband emission with very long decay times typical of d-d transitions.

During a nanomineralogy investigation of the Tissint Martian meteorite, we discovered the new shock-induced mineral tissintite, (Ca,Na,□)AlSi_2O_6, which is named after Tissint, Morocco, where the host meteorite fell. This phase provides new insights into shock conditions and impact processes on Mars. Here, we emphasize the origin of tissintite (IMA 2013-027) and demonstrate how nanomineralogy can play an important role in meteorite and Mars rock research.

Joteite (IMA2012-091), Ca_2CuAl[AsO_4][AsO_3(OH)]_2(OH)_2•5H_2O, is a new mineral from the Jote mine, Tierra Amarilla, Copiapó Province, Atacama, Chile. The mineral is a late-stage, lowtemperature, secondary mineral occurring with conichalcite, mansfieldite, pharmacoalumite, pharmacosiderite and scorodite in narrow seams and vughs in the oxidized upper portion of a hydrothermal sulfide vein hosted by volcanoclastic rocks. Crystals occur as sky-blue to greenish-blue thin blades, flattened and twinned on {001}, up to ~300 µm in length, and exhibiting the forms {001}, {010}, {110}, {210} and {111}. The blades are commonly intergrown in wheat-sheaf-like bundles, less commonly in sprays, and sometimes aggregated as dense crusts and cavity linings. The mineral is transparent and has a very pale blue streak and vitreous lustre. The Mohs hardness is estimated at 2 to 3, the tenacity is brittle, and the fracture is curved. It has one perfect cleavage on {001}. The calculated density based on the empirical formula is 3.056 g/cm^3. It is optically biaxial (–) with α = 1.634(1), β = 1.644(1), γ = 1.651(1) (white light), 2V_(meas) = 78(2)° and 2V_(calc) = 79.4°. The mineral exhibits weak dispersion, r < v. The optical orientation is X ≈ c*; Y ≈ b*. The pleochroism is Z (greenish blue) > Y (pale greenish blue) > X (colourless). The normalized electron-microprobe analyses (average of 5) provided: CaO 15.70, CuO 11.22, Al_2O_38.32, As_2O_546.62, H_2O 18.14 (structure), total 100 wt.%. The empirical formula (based on 19 O a.p.f.u.) is: Ca_(1.98)Cu_(1.00)Al_(1.15)As_(2.87)H_(14.24)O_(19). The mineral is slowly soluble in cold, concentrated HCl. Joteite is triclinic, P1, with the cell parameters: a = 6.0530(2), b = 10.2329(3), c = 12.9112(4) Å, a = 87.572(2), b = 78.480(2), g = 78.697(2)°, V = 768.40(4) Å^3 and Z = 2. The eight strongest lines in the X-ray powder diffraction pattern are [d_(obs) Å (I)(hkl)]: 12.76(100)(001), 5.009(23)(020), 4.206(26)(120,003,121), 3.92(24)(022,022,102), 3.40(25)(113), 3.233(19)(031,023,123,023), 2.97(132,201) and 2.91(15)(122,113). In the structure of joteite (R_1 = 7.72% for 6003 F_o > 4σF), AsO_4 and AsO_3 (OH) tetrahedra, AlO_6 octahedra and Cu^(2+)O_5 square pyramids share corners to form sheets parallel to {001}. In addition, 7- and 8-coordinate Ca polyhedra link to the periphery of the sheets yielding thick slabs. Between the slabs are unconnected AsO_3(OH) tetrahedra, which link the slabs only via hydrogen bonding. The Raman spectrum shows features consistent with OH and/or H_2O in multiple structural environments. The region between the slabs may host excess Al in place of some As.

The development of an in-situ geochronology capability for Mars and other planetary surfaces has the potential to fundamentally change our understanding of the evolution of terrestrial bodies in the Solar System. For Mars specifically, many of our most basic scientific questions about the geologic history of the planet require knowledge of the absolute time at which an event or process took place on its surface. For instance, what was the age and rate of early Martian climate change recorded in the mineralogy and morphology of surface lithologies (e.g., [1])? In-situ ages from a few select locations within the globally established stratigraphy of Mars would be transformative, enabling us to place direct chronologic constraints on the timing and rates of impact, volcanic, sedimentary, and aqueous processes on the Martian surface.

The development of an in-situ geochronology capability for Mars and other planetary surfaces has the potential to fundamentally change our understanding of the evolution of terrestrial bodies in the Solar System. For Mars specifically, many of our most basic scientific questions about the geologic history of the planet require accurate knowledge of the absolute time at which an event or process took place. For instance, what was the age and rate of early Martian climate change faithfully recorded in the mineralogy and morphology of surface lithologies (e.g., [1])? Currently, our only means of assessing the absolute age of a surface on a planetary body is through the use of crater counting statistics. This technique is fraught with uncertainty for planets with active geologic surfaces, on the order of billions of years in some cases (e.g., [2]). Accordingly, there is much room for improvement in our understanding of the absolute chronology of the surfaces of rocky planetary bodies.

During our nano-mineralogy investigation of the Allende meteorite, we discovered a unique corundum-rich cluster of irregular micrometer-sized refractory grains in a type IA chondrule. The presence of relatively oxidized (rutile) and highly reduced (a new mineral Ti_2O_3, khamrabaevite) phases in the same cluster reflects distinctly different environments prior to incorporation of the cluster into the chondrule. To our knowledge, this is the first occurrence of such a cluster. Investigation of phases that are clearly exotic to the host chondrule and may predate its formation can provide not only important constraints on the materials present when chondrules formed and the enviroments within or outside the Protoplanetary disk, but also on the chondrule formation event. Herein we report our prelimary results on the mineralogy of these grains and the overall petrology of their host chondrule.

During our nano-mineralogy investigation of the Allende meteorite, we discovered two new minerals that occur as micro- to nano-crystals in refractory inclusions: Allendeite, Sc_4Zr_3O_(12), a new Scand Zr-rich oxide; and hexamolybdenum, (Mo,Ru,Fe), a Mo-dominant alloy. Allendeite, which may be an important ultra-refractory carrier linking Zr-, Sc- oxides and the more common Sc-, Zr-enriched clinopyroxenes (Cpx) in CAIs, hosts perovskite (Pv), spinel (Sp), Os-Ir-W-Mo alloys, and hexamolybdenum. The observation of two structurally and chemically distinct highly refractory, low-Pt alloy minerals not associated with Fe-Ni alloys provides the first direct physical evidence for at least two separate carriers of the highly refractory metals in CAIs. Hexamolybdenum links Osrich and Pt-rich meteoritic alloys and may be a precursor of the latter. Both new minerals have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA 2007-027, 029).

Despite the predominately mafic character of martian surface rocks, silica-rich materials have long been predicted to occur on Mars; recently, those predictions have been validated. CRISM spectra from numerous regions of Mars have revealed H_2O and OH-bearing phases most consistent with amorphous silica. Additionally, the detection of high-silica materials at Home Plate by MER Spirit implied aqueous alteration and leaching in a volcanic environment [3]. In order to fully understand the environments in which silica-rich materials are formed on Mars, it is useful to study silica in analogous terrestrial settings. We focus on silica and Fe-Ti oxide coatings in the Ka’u Desert on the island of Hawaii, an analog to Mars characterized by low levels of rainfall and strong acid-sulfate alteration processes [4]. Many formation mechanisms for these coatings have been proposed, including dissolution of wind-blown tephra [5], leaching of volcanic glass [6], and vapor deposition [7]. We focus on a suite of samples from the 1974 Kilauea pahoehoe flow, collected in 2003. The chemistry and morphology of these coatings were previously presented [8]. Here we present new morphological, spectral and isotopic analyses of the coating suite. The goal of the study is to characterize the coatings and their formation mechanism and describe the implications for silica mobility on Mars.

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