Ore deposits of the Velardena District, Mexico

Spurr, Josiah Edward; Garrey, G. H.

doi:10.2113/gsecongeo.3.8.688

Cited by 7 publications

(2 citation statements)

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“…Only a few minerals that contain both silicate and carbonate groups exist, three of them belonging to the CaO-CO 2 -SiO 2 system: Ca 7 (SiO 4 ) 3 (CO 3 ) galuskinite 9 , Ca 5 (SiO 4 ) 2 (CO 3 ) spurrite 10 , and Ca 5 (Si 2 O 7 )(CO 3 ) 2 tilleyite 11 . They form in the metamorphic zone between limestones (sharp contact with marble, mainly composed of CaCO 3 calcite) and igneous rocks (CaSiO 3 wollastonite and other silicate minerals), at low pressures and high temperatures 12,13 .…”

Section: Introductionmentioning

confidence: 99%

Post-tilleyite, a dense calcium silicate-carbonate phase

Santamarı́a-Pérez

Ruiz‐Fuertes

Peña-Álvarez

et al. 2019

Sci Rep

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Calcium carbonate is a relevant constituent of the Earth’s crust that is transferred into the deep Earth through the subduction process. Its chemical interaction with calcium-rich silicates at high temperatures give rise to the formation of mixed silicate-carbonate minerals, but the structural behavior of these phases under compression is not known. Here we report the existence of a dense polymorph of Ca 5 (Si 2 O 7 )(CO 3 ) 2 tilleyite above 8 GPa. We have structurally characterized the two phases at high pressures and temperatures, determined their equations of state and analyzed the evolution of the polyhedral units under compression. This has been possible thanks to the agreement between our powder and single-crystal XRD experiments, Raman spectroscopy measurements and ab-initio simulations. The presence of multiple cation sites, with variable volume and coordination number (6–9) and different polyhedral compressibilities, together with the observation of significant amounts of alumina in compositions of some natural tilleyite assemblages, suggests that post-tilleyite structure has the potential to accommodate cations with different sizes and valencies.

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Section: Introductionmentioning

confidence: 99%

Post-tilleyite, a dense calcium silicate-carbonate phase

Santamarı́a-Pérez

Ruiz‐Fuertes

Peña-Álvarez

et al. 2019

Sci Rep

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“…The existence of the mineral spurrite was first reported by the American mineralogists Josiah Edward Spurr and George Garrey in 1908 and later described and named that year by Fred Eugene Wright . This calcium silicate carbonate mineral, with a nominal Ca 5 (SiO 4 ) 2 (CO 3 ) formula, is the product of thermal metamorphism and chemical alteration in contact areas between hot acid magmas and rocks bearing calcium carbonate.…”

Section: Introductionmentioning

confidence: 99%

Structural Behavior of Natural Silicate–Carbonate Spurrite Mineral, Ca₅(SiO₄)₂(CO₃), under High-Pressure, High-Temperature Conditions

et al. 2017

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We report on high-pressure and high-temperature angle-dispersive synchrotron X-ray diffraction and high-pressure Raman data up to 27 GPa and 700 K for natural silicate carbonate Ca(SiO)(CO) spurrite mineral. No phase transition was found in the studied P-T range. The room-temperature bulk modulus of spurrite using Ne as the pressure-transmitting medium is B = 77(1) GPa with a first-pressure derivative of B' = 5.9(2). The structure compression is highly anisotropic, the b axis being approximately 30% more compressible than the a and c axes. The volumetric thermal expansivity value around 8 GPa was estimated to be 4.1(3) × 10 K. A comparison with intimately related minerals CaCO calcite and aragonite and β-CaSiO larnite shows that, as the composition and structural features of spurrite suggest, its compressibility and thermal expansivity lie between those of the silicate and carbonate end members. The crystal chemistry and thermodynamic properties of spurrite are discussed.

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