Donald H. Lindsley

QUILF: a Pascal program to assess equilibria among Fe-Mg-Mn-Ti oxides, pyroxenes, olivine, and quartz

The present invention relates to a combination display, storing and dispensing instrumentality, in particular for use in connection with coloring matters, cosmetic, and semisolid and similar plastic masses and applies more specifically to lipstick testing and like makeup equipment, which is generally exposed to view and generally tested when employed in specialty stores on counters thereof and other establishments.

Acid‐sulfate weathering of synthetic Martian basalt: The acid fog model revisited

The acid fog model has received considerable attention as a model of soil formation on Mars. Previous evaluations of this model have focused on experimental weathering of terrestrial basalt samples. However, these samples differ significantly from what now is thought to be typical of Martian basalt. The acid fog model is tested here using synthetic basaltic analogs derived from Mars Pathfinder soil and rock compositions. Reaction of synthetic basalt with various acidic solutions and subsequent evaporation has led to the formation of several putative secondary mineral phases. Many of these phases were not produced in prior experimental studies aimed at aqueous interactions on Mars. Of these alteration phases, Mg, Fe, Ca, and Al sulfates were identified. In addition, secondary ferric oxide phases formed via rapid Fe oxidation under relatively high pH levels buffered by basalt dissolution. Amorphous silica is a ubiquitous product in these experiments and has formed by precipitation from solution and by the dissolution of minerals and glasses leaving behind leached surface layers composed of residual silica. The secondary products formed in these experiments demonstrate the importance of primary mineralogy when testing models of aqueous interactions on Mars. New constraints are placed on both the reactivity of primary basalt and the secondary mineralogy present at the Martian surface. Copyright 2004 by the American Geophysical Union.

Stability of titanian clinohumite: Experiments and thermodynamic analysis

Reversed hydrothermal experiments on a natural titanoclinohumite [Ti-Cl; approximate formula Mg7.5FeTi0.5O16(OH)] show that it breaks down at 475°±11° C (3.5 kbar), 620°±11° C (14 kbar) and 675°±8° C (21 kbar) to the assemblage olivine +ilmenite+vapor. An internal-consistency analysis of the data yields ΔrGs/0(298 K, 1 bar)=36,760±3,326 cal (mole Ti-Cl)−1. ΔrSs/0(298 K, 1 bar)=34.14±5.91 cal deg−1(mole Ti-Cl)−1. Linear correlation coefficient rG−S≈1.0. A solution model that accounts for TiO2-M(OH)2 and F-OH substitution shows that the results for our nearly F-free Ti-Cl are in reasonable agreement with the unreversed breakdown experiments of Mer-rill et al. (1972) on a F-bearing Ti-Cl.Because fluorine is necessary to stabilize Ti-Cl under mantle conditions, we suggest that Ti-Cl is much more likely to be a “storage device” for fluorine than for water in the mantle.

A valid Margules formulation for an asymmetric ternary solution - Revision of the olivine-ilmenite thermometer, with applications

Abstract The olivine-ilmenite thermometer of Andersen and Lindsley (1979) was based on an incorrect formulation for the excess free energy of an asymmetric ternary solution. A valid formulation is derived and used to revise the parameters of the olivine-ilmenite thermometer. For olivine and ilmenite that have equilibrated above 700°C, temperature can be calculated from: T(°C) = −273 +¦-12549 + P[0.03X fa + 0.01099(X gk −X il )−0.062] + 10496 X fa + 5767(X gk −X il ) + X hem (38602−141550X il −47183X gk )|/[5.67−R ln K D + 6.52X fa + 3.09(X gk −X il ) + X hem (16.49−109.46 X il −36.49X gk )] with K d = (X il X fo ) (X gk X fa ) . The revised model gives Wil·gkG = 5767−3.09T + 0.011P and ΔGexch = 7301 − 8.9T − 0.047P (T in K, P in bars). Applications include Apollo 17 breccias and kimberlites.

Chemical systematics among the moldavite tektites

The compositional variations that occur among the moldavite tektites are caused principally by incomplete mixing of two components during fusion. With the possible exception of silica, there is no evidence for significant losses of volatile species by fractional vaporization. Chemical constraints have been calculated for the two source-materials that contributed to the moldavites. If these tektites were formed by impact fusion, as is commonly believed, then the compositional systematics preserved within the moldavites suggest that hypersonic flow and ejection of impact melts are orderly processes. Insights gained from the study of tektites should prove useful in interpreting the chemistries of impact glasses from other bodies in the solar system.

(Ca,Mg)2Si2O6 clinopyroxenes: A solution model based on nonconvergent site-disorder

AbstractExperiments at high pressure and temperature indicate that excess Ca may be dissolved in diopside. If the (Ca, Mg)2Si2O6 clinopyroxene solution extends to more Ca-rich compositions than CaMgSi2O6, macroscopic regular solution models cannot strictly be applied to this system. A nonconvergent site-disorder model, such as that proposed by Thompson (1969, 1970), may be more appropriate. We have modified Thompsons model to include asymmetric excess parameters and have used a linear least-squares technique to fit the available experimental data for Ca-Mg orthopyroxene-clinopyroxene equilibria and Fe-free pigeonite stability to this model. The model expressions for equilibrium conditions

Chemical systematics among the Moldavite Tektites: Reply to W. von Engelhardt

\mu _{{\text{Mg}}_{\text{2}} {\text{Si}}_{\text{2}} {\text{O}}_{\text{6}} }^{{\text{opx}}} = \mu _{{\text{Mg}}_{\text{2}} {\text{Si}}_{\text{2}} {\text{O}}_{\text{6}} }^{{\text{cpx}}}

Effects of differential recoil-free fraction on ordering and site occupancies in Mössbauer spectroscopy of orthopyroxenes

(reaction A) and