Changes

file:sem-xrd-cl-and-xf-methods_fig2.png|{{figure number|2}}X-ray diffraction configuration. Knowledge of the wavelength (X) and angle of incidence allows the ''d'' spacing to be calculated.

file:sem-xrd-cl-and-xf-methods_fig2.png|{{figure number|2}}X-ray diffraction configuration. Knowledge of the wavelength (X) and angle of incidence allows the ''d'' spacing to be calculated.

file:sem-xrd-cl-and-xf-methods_fig3.png|{{figure number|3}}X-ray diffraction patterns.

file:sem-xrd-cl-and-xf-methods_fig3.png|{{figure number|3}}X-ray diffraction patterns.

file:sem-xrd-cl-and-xf-methods_fig4.png|{{figure number|4}}Schematic drawing showing how a typical cathodoluminescence system works. Depending on the manufacturer, the location of the cathode tube may differ.]]

file:sem-xrd-cl-and-xf-methods_fig4.png|{{figure number|4}}Schematic drawing showing how a typical cathodoluminescence system works. Depending on the manufacturer, the location of the cathode tube may differ.

file:sem-xrd-cl-and-xf-methods_fig5.png|{{figure number|5}}A photomicrograph taken under cathodoluminescence showing concentric zoning in dolomite cement. High Mn⁺² dolomite shows up as bright bands and higher Fe⁺² dolomite as dark bands. Copyright: W. J. Myers.

file:sem-xrd-cl-and-xf-methods_fig5.png|{{figure number|5}}A photomicrograph taken under cathodoluminescence showing concentric zoning in dolomite cement. High Mn⁺² dolomite shows up as bright bands and higher Fe⁺² dolomite as dark bands. Copyright: W. J. Myers.

file:sem-xrd-cl-and-xf-methods_fig6.png|{{figure number|6}}(a) X-ray fluoroscopy slab photograph and (b) plane light slab photograph of a Pennsylvanian sandstone from Oklahoma.

file:sem-xrd-cl-and-xf-methods_fig6.png|{{figure number|6}}(a) X-ray fluoroscopy slab photograph and (b) plane light slab photograph of a Pennsylvanian sandstone from Oklahoma.

Nonminerals such as solid hydrocarbons or glass cannot be identified by XRD because they lack sufficient internal structure.

Nonminerals such as solid hydrocarbons or glass cannot be identified by XRD because they lack sufficient internal structure.

Determination of bulk rock mineralogy is obtained from combined diffraction analysis of bulk powder and oriented mounts. Powder mounts are best for identification of nonplaty minerals. Platy minerals are best analyzed in slurries dried on metal, glass, or ceramic holders. This is especially true for clays with particle sizes ≤5 μm. Abundances are then determined by measuring peak intensity or half area for the diffraction peaks of the major three to five diffraction peaks of each mineral ([[:file:sem-xrd-cl-and-xf-methods_fig3.png|Figure 3]]). A limitation of this method is the inability to determine abundances of mineral species (such as quartz from chert) or polymineral grains (such as granite from separate feldspar and quartz).

Determination of bulk rock mineralogy is obtained from combined diffraction analysis of bulk powder and oriented mounts. Powder mounts are best for identification of nonplaty minerals. Platy minerals are best analyzed in slurries dried on metal, glass, or ceramic holders. This is especially true for clays with particle sizes ≤5 μm. Abundances are then determined by measuring peak intensity or half area for the diffraction peaks of the major three to five diffraction peaks of each mineral ([[:file:sem-xrd-cl-and-xf-methods_fig3.png|Figure 3]]). A limitation of this method is the inability to determine abundances of mineral species (such as [[quartz]] from [[chert]]) or polymineral grains (such as granite from separate feldspar and quartz).

==Cathodoluminescence (CL)==

==Cathodoluminescence (CL)==

In CL, electrons from a cold cathode discharge tube strike a rock surface in a vacuum chamber ([[:file:sem-xrd-cl-and-xf-methods_fig4.png|Figure 4]]). In a strong vacuum, energy imparted to electrons in activator ions within the grain causes luminescence. The principle activator ions are manganese and lead.<ref name=pt05r107>Machel, H-G., 1985, Cathodoluminescence in calcite and dolomite and its chemical interpretation: Geoscience Canada, v. 12, p. 139–147.</ref> Concentrations need be in the 100 ppm range to affect the grain. Other rare earth elements such as dysprosium are also activators. Ferric iron (+3) is the most common quenching ion. The emitted color, when observed, shows the zonations in activator ion concentrations related to the type of crystallization or thermal histories of the host minerals ([[:file:sem-xrd-cl-and-xf-methods_fig5.png|Figure 5]]). Lattice defect structures in quartz are also thought to cause some CL in quartz.

In CL, electrons from a cold cathode discharge tube strike a rock surface in a vacuum chamber ([[:file:sem-xrd-cl-and-xf-methods_fig4.png|Figure 4]]). In a strong vacuum, energy imparted to electrons in activator ions within the grain causes luminescence. The principle activator ions are manganese and lead.<ref name=pt05r107>Machel, H-G., 1985, Cathodoluminescence in calcite and dolomite and its chemical interpretation: Geoscience Canada, v. 12, p. 139–147.</ref> Concentrations need be in the 100 ppm range to affect the grain. Other rare earth elements such as dysprosium are also activators. Ferric iron (+3) is the most common quenching ion. The emitted color, when observed, shows the zonations in activator ion concentrations related to the type of crystallization or thermal histories of the host minerals ([[:file:sem-xrd-cl-and-xf-methods_fig5.png|Figure 5]]). Lattice defect structures in [[quartz]] are also thought to cause some CL in quartz.

The most frequent application of CL is in carbonate diagenesis (e.g.,  Machel,<ref name=pt05r107 /> Myers<ref name=pt05r120>Myers, W. J., 1978, Carbonate cements—their regional distribution and interpretation in Mississippian limestones of southwestern New Mexico: Sedimentology, v. 25, p. 371–399.</ref>). As has been shown by Sippel,<ref name=pt05r147>Sippel, R. T., 1968, Sandstone petrology, evidence from luminescence petrography: Journal of Sedimentary Petrology, v. 38, p. 530–554.</ref> it is also useful in determining paragenesis of siliciclastic rocks. It is particularly useful in interpreting original composition and texture in recrystallized or dolomitized strata.

The most frequent application of CL is in [[carbonate diagenesis]] (e.g.,  Machel,<ref name=pt05r107 /> Myers<ref name=pt05r120>Myers, W. J., 1978, Carbonate cements—their regional distribution and interpretation in Mississippian limestones of southwestern New Mexico: Sedimentology, v. 25, p. 371–399.</ref>). As has been shown by Sippel,<ref name=pt05r147>Sippel, R. T., 1968, Sandstone petrology, evidence from luminescence petrography: Journal of Sedimentary Petrology, v. 38, p. 530–554.</ref> it is also useful in determining paragenesis of siliciclastic rocks. It is particularly useful in interpreting original composition and texture in recrystallized or dolomitized strata.

==X-ray fluoroscopy (XF)==

==X-ray fluoroscopy (XF)==

[[Category:Laboratory methods]]

[[Category:Laboratory methods]]