Common naturally occurring orthosilicates can be grouped into those in which the major non-tetrahedral cations are (1) FeII and/or Mg, plus or minus Al (olivine, pyralspite garnets, staurolite); (2) Al (Al2SiO5 polymorphs), or (3) Zr. Feand Mg-bearing orthosilicates have the weakest bonds between non-tetrahedral cations and structural oxygen (M-O bonds), and zircon the strongest, with Al-O bond...

Chemical weathering rates and erosion rates of granitic till in northern Sweden have been estimated. The present-day chemical weathering rate is compared with the long-term average weathering rate since the last deglaciation approximately 8,700 years ago. Also, the present-day release rates of major and trace elements due to chemical weathering are compared with the mobility of these elements i...

Space weathering causes the change in optical properties, such as darkening, reddening, and decrease of absorption depths of the planetary surfaces. Two competing processes have been proposed so far as the main mechanism of such space weathering; hydrogen irradiation by solar wind and bombardment of micrometeorites. We use the new data set obtained by Spectral Profiler (SP) onboard SELENE/Kaguy...

STATEMENT OF PROBLEM Maxillofacial prostheses are serviceable for approximately 6 months, after which they need to be refabricated because of the deterioration of color and physical properties. PURPOSE This third article in a 3-part series evaluated the color stability of commonly used colorant-elastomer combinations as a result of exposure to weathering. METHODS AND MATERIAL Fifteen specim...

Ectomycorrhizal fungi may make a significant contribution to mineral weathering in temperate and boreal forests. It is important to know how this weathering activity will be affected by the changing nutrient demands of forests impacted by global change and nitrogen deposition. This review examines what is known about how plants sense and respond to nutrient demand and discusses the existing lit...

Continental crust rises higher than oceanic crust because it is less dense: It is rich in Si and poor in Mg. However, basalt, which is derived from magma, is denser and has a higher ratio of Mg to Si than the rock that makes up mature continental crust. Cin-Ty Lee et al. argue that chemical weathering alters the composition of continental crust as it ages and helps give it its more buoyant char...

Introduction: We present evidence that space weathering manifests itself at near-ultraviolet wavelengths as a bluing of the spectrum, in contrast with the spectral reddening that has been seen at visible-near-IR wavelengths. This UV bluing often results in a spectral reversal, where surfaces that are bright at visible-near-IR wavelengths are relatively dark at UV wavelengths, and vice-versa. Fu...

Introduction: Chemical weathering and petrologic trends of the martian surface have been estimated from thermal infrared (TIR) spectral models from the Thermal Emission Spectrometer (TES) and Mini-TES on the Spirit and Opportunity rovers [1,2]. Interpretations of chemical data from APXS on the MER rovers and TIR data from TES and the Thermal Emission Imaging System (THEMIS) suggest planet-wide ...