Data determined using a multianvil press are given for liquidus phase relations in the system diopside – forsterite – enstatite (CaMgSi2O6 – Mg2SiO4 – MgSiO3) and extend for a limited distance into the larger ternary system diopside – forsterite – quartz at 5.1 GPa. In the system diopside–enstatite, which cuts across the system diopside – forsterite – quartz and divides it into two smaller tern...

Introduction: Because they are dominated by enstatite, a nearly FeO-free pyroxene, and Si-bearing FeNi metal, along with minor amounts of unusual monosulfides such as niningerite (MgS), oldhamite (CaS) and alabandite (MnS), the enstatite chondrites have long been thought to have formed under extremely reducing conditions [1,2]. Like the ordinary chondrites, enstatite chondrites exhibit a range ...

Enstatite is a ubiquitous phase in chondritic meteorites, interplanetary dust particles, and cometary samples. In equilibrium condensation models, enstatite predicted to condense via reaction between pre-condensed forsterite gaseous SiO. However, previous studies have shown that some enstatites chondrite matrices AOAs do not genetic relationship with forsterite, arguing against formation by the...

[1] EL chondrites exhibit larger average metal grain sizes than EH chondrites, a difference attributed by Easton [1983] to metamorphic coarsening, as most EL chondrites are equilibrated, and most EH chondrites are unequilibrated. In this paper, we present metal grain size data for three unequilbrated EL3 chondrites (PCA 91020; ALH 85119; MAC 88180) , and three EH3 chondrites (ALH 84170; PCA 910...

Sepiolite deposits have been recently discovered in northeastern Iran. However, there is still little information about its physicochemical and mineralogical characteristics. Therefore, the collapse of the sepiolite (with sizes of < 63 μm) structure induced by temperature elevation in an electric furnace at 350, 550, and 850 °C for 4 hours was studied using X-ray diffraction (XRD) in combinatio...

[1] We present the analysis of 205 spatially resolved measurements of the surface composition of Mercury from MESSENGER’s X-Ray Spectrometer. The surface footprints of these measurements are categorized according to geological terrain. Northern smooth plains deposits and the plains interior to the Caloris basin differ compositionally from older terrain on Mercury. The older terrain generally ha...

We report mass-dependent and mass-independent Ca isotopic variations in nine chondrites from three groups: carbonaceous, ordinary and enstatite chondrites. There is about 0.25‰ per amu, i.e., 1‰ in Ca/Ca, variation in chondrites: carbonaceous chondrites have the lightest Ca isotopes, enstatite chondrites have modeled bulk Earth like Ca isotopes, and ordinary chondrites are in between. The corre...

Buseckite (IMA 2011-070), (Fe,Zn,Mn)S, is the Fe-dominant analog of wurtzite, a new member of the wurtzite group discovered in Zakłodzie, and an ungrouped enstatite-rich achondrite. The type material occurs as single-crystal grains (4–20 μm in size) in contact with two or more of enstatite, plagioclase, troilite, tridymite, quartz, and sinoite. Low-Ni iron, martensitic iron, schreibersite, keil...