groundmass उदाहरण वाक्य
उदाहरण वाक्य
- Iddingsite forms from the weathering of basalt in the presence of liquid water and can be described as a phenocryst, i . e . it has megascopically visible crystals in a fine-grained groundmass of a porphyritic rock.
- The groundmass contains interstitial quartz or tridymite or cristobalite . " Olivine tholeiite " has augite and orthopyroxene or pigeonite with abundant olivine, but olivine may have rims of pyroxene and is unlikely to be present in the groundmass.
- The groundmass contains interstitial quartz or tridymite or cristobalite . " Olivine tholeiite " has augite and orthopyroxene or pigeonite with abundant olivine, but olivine may have rims of pyroxene and is unlikely to be present in the groundmass.
- The groundmass mineralogy, which more closely resembles a true composition of the igneous rock, is dominated by carbonate and significant amounts of forsteritic olivine, with lesser amounts of pyrope garnet, Cr-diopside, magnesian ilmenite and spinel.
- The groundmass of these rocks is often aphanitic microcrystalline, with a web of minute feldspars mixed with interstitial grains of quartz or tridymite; but in many dacites it is largely vitreous, while in others it is felsitic or cryptocrystalline.
- However, in aphanites, or rocks with phenocrysts clearly out of equilibrium with the groundmass, a normative mineral calculation is often the best to understand the evolution of the rock and its relationship to other igneous rocks in the region.
- However, the texture is only a subordinate part of classifying volcanic rocks, as most often there needs to be chemical information gleaned from rocks with extremely fine-grained groundmass or from airfall tuffs, which may be formed from volcanic ash.
- "' Hyalopilitic "'is a groundmass, which is visible only under magnification with a petrographic microscope, that contains a mixture of very fine-grained mineral crystals either mixed with natural volcanic glass, or surrounded by thin bands of volcanic glass.
- In Australia, silcrete was widely used by Aboriginal people for stone tool manufacture, and as such, it was a tradeable commodity, and silcrete tools can be found in areas that have no silcrete groundmass at all, similar to the European use of flint.
- The name " picrite " can also be applied to an olivine-rich alkali basalt : such picrite consists largely of phenocrysts of olivine and titanium-rich augite pyroxene with minor plagioclase set in a groundmass of augite and more sodic plagioclase and perhaps analcite and biotite.