Formation of Mica During Experimental Alteration of K-Feldspar

Abstract

Abstract--Experimental alterations of K-feldspar in distiUed-deionized water at 150", 175", 200*, and 225*(2 were performed. The alteration products and dissolution mechanism of K-feldspar were examined by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopy (XPS). SEM, TEM, and EDX clearly showed formation of fibrous boehmite less than 1.0 ~m in length at the early alteration stages. The boehmite fibers decreased in abundance and rounded platy 1 M mica was produced as alteration proceeded. The mica exhibited initially angular shaped small flakes of 0.69 tzm in average size, which developed to rounded platy particles of 1.97/~m. The main chemical reactions occurring in this experimental system can be expressed by: KAISi3Os + 6H20 + H + --~ AdO(OH) + 3H4SIO4 + K +, [K=feldspar] [boehmite]3 KAISi3Os + 12H20 ~ KA13Si3010(OH)2 + 2K + + 6H4SIO4 + 22H +.XPS showed no significant changes in intensities of photoelectron lines excited from K, Si, and A1 in the K-feldspar surface before and after alteration, however the K/Si molar ratios in the solutions were considerably smaller than that of the original K-feldspar. The results of XPS strongly indicate that no dealkalized layer was produced on the surface, and that dissolution of K-feldspar in aqueous solution proceeded congruently by a surface-reaction mechanism. The discrepancy of mass balance in the solutions may be mainly caused by adsorption of K on the surface of boehmite.

Synthesis, Characterization, Uses and Applications of Porous Clays Heterostructures: A Review

“…The value of this reflection varies as function of the hydration sphere of the cation used to counterbalance the charge of the phyllosilicate. Considering that the thickness of a single layer is 0.96 nm, the distance between adjacent layers is in the range of 0.20–0.56 nm, which is typical of the hydrated clays …”

The Behavior of Water in Orthoclase Crystal and Its Implications for Feldspar Alteration

“…Feldspar alteration is a consistent concern for geologists, mineralogists, and environment scientists [1,[18][19][20][21][22]. Interestingly, fine-grained sericite was reported to occur as an alteration product in the interior of feldspar crystals [23][24][25][26]. However, the alteration that occurs in the interior of feldspar crystals is not fully understood yet.…”

VIPERnano: Improved Live Cell Intracellular Protein Tracking

“…In this method, an endogenous protein−peptide fusion is labeled by incubation and dimerization with a second peptide conjugated to a fluorophore as shown in Figure 2a. [13][14][15][16] We recently developed VIP (versatile interacting peptide) tags, which use a heterodimeric coiled-coil between two peptides as seen in Figure 2a. 13,14 In the latest variation, VIPER, a fusion peptide tag (CoilE) binds with reporter-conjugated peptide (CoilR) and is used to label both extracellular and intracellular proteins.…”

“…13,14 Here we sought to improve the VIP tags by introducing a technology for accessing intracellular targets in living cells. 13,15,16 VIPER nano (Versitle Interacting Peptides E and R with hollow gold nanoshells) demonstrates the capability of live cell imaging with small fluorescent tags using the VIPER coils attached to hollow gold nanoshells (HGNs) for light-activated protein labeling. 17−19 This delivery strategy relies on orthogonal linkers attached to the HGN surface, one for internalization using a cell penetrating peptide and the other for CoilR attachment.…”