Quantitative analyses of powdered multi-minerallic carbonate aggregates using a portable Raman spectrometer

Abstract

Mg-Ca carbonates are an important group of industrial minerals, which frequently occur intimately intermixed in natural settings and are traditionally assessed for phase purity by X‑ray diffraction (XRD). In this study Raman spectroscopy is employed to quantify the modal abundance of hydromagnesite [Mg 5(CO3)4(OH)2·4H2O], huntite [CaMg3(CO3)4], dolomite [MgCa(CO3)2], and magnesite [MgCO3], in powdered mixtures constructed from fabricated reference materials. Particle size distributions were assessed by scanning electron microscopy and laser diffraction. Raman analyses performed using a portable instrument were conducted at 25 °C and at atmospheric pressure. XRD was employed to validate the accuracy and precision of Raman measurements. Monovariable and multivariable methods were employed to provide quaternary quantification from the spectroscopic data. For monovariable calibration the amplitude of the peaks was plotted against the measured weight ratios of the four mineral phases. Overlapping bands were resolved using the Gaussian Lorentzian method. Chemometric methods were used to perform the multivariable calibration. The overall lowest error on component values was obtained by principal component regression with application of standard normal variate correction. The quantifications derived by Raman spectroscopy and XRD show close agreement. Hence, evidence suggests that a reliable four-way calibration program to screen the purity of carbonate assemblages can be constructed, providing particle size effects are constrained and spectroscopic operating conditions are uniform

Particular H2O dissolution mechanism in iron‐rich melt: Application to martian basaltic melt genesis

“…The Raman spectroscopy is a dedicated tool used to investigate qualitatively and quantitatively both crystallized and amorphous materials. Spectroscopic studies were achieved to establish calibrations from Raman spectra in crystallized materials (e.g., these works). Many studies on amorphous materials based on the investigation of CO 2 and S behaviors in a silicate melt have led to subsequent calibrations (e.g., these works).…”

The Effect of the Particle Size on the Fundamental Vibrations of the [CO32–] Anion in Calcite

“…Spectral intensities (infrared absorption and Raman intensity) are generally considered proportional to concentration by Boguer-Lambert-Beer Law or by other mathematical formulae derived from the fundamental law of quantitative spectroscopy. [3][4][5][6] However infrared spectra acquired from powdered calcite and other mineral species are known to undergo changes as a function of particle grain size. 2,7-9 The effect of particle size on the spectral resolution of the fundamental vibrations of the [CO3 2-] anion in calcite were identified in infrared emission studies and have been divided into three classes of behavior.…”

Future Developments and Innovations in High-Resolution Core Scanning

“…Raman is a light scattering technique, and normally all that is required for spectrum collection is to place the sample in the excitation beam and analyse the scattered light. There are several varieties of the technique, termed Dispersive Raman (Smith and Clark 2004;Izake 2010), FT-Raman (Fourier Transform Raman; Cangemi et al 2010;Kristova et al 2013) and Time-resolved Raman spectroscopy (Fig. 27.7) (Blacksberg and Rossman 2010).…”