What is the standard thickness of a thin section?
Thin sections are 30 µm (0.03 mm) thick slices of rock, minerals, concrete, mortar, or other materials that are mounted to a glass microscope slide with epoxy and topped with a glass coverslip.
What is petrographic thin section?
In optical mineralogy and petrography, a thin section (or petrographic thin section) is a thin slice of a rock or mineral sample, prepared in a laboratory, for use with a polarizing petrographic microscope, electron microscope and electron microprobe.
How does a petrographic microscope identify a mineral?
One approach is utilized for transparent crystals that are analyzed with transmitted light. The second is used for opaque crystals. In this approach, a modified polarizing microscope is used and light is reflected from a highly polished surface and then analyzed using similar methods as for transmitted light.
What are petrographic characteristics?
The important petrographic characteristics influencing mechanical behaviour include modal concentration and grain size of individual minerals, mean grain size of rock and distribution of grain size within a rock. Recrystallization of minerals along boundaries has a pronounced effect on increased strength of granites.
What is petrographic analysis?
Petrographic Analysis (ASTM C856) – A microstructural examination by optical and scanning electron microscopy (SEM) of the paste and aggregate on a prepared sample of concrete to look for features such as degree of cement hydration, microcracking, reaction products, breakdown of aggregate and evidence of poor freeze- …
How do you make a petrographic thin section?
A thin sliver of rock is cut from the sample with a diamond saw and ground optically flat. It is then mounted on a glass slide and then ground smooth using progressively finer abrasive grit until the sample is only 30 μm thick.
What is the meaning of petrographic?
Definition of petrography : the description and systematic classification of rocks.
How do you identify minerals in a thin section?
We use cross-polarized light to learn a crystal’s optic class and optic sign, to measure extinction angles and sign of elongation, and to measure 2V. A combination of optical properties allows us to identify minerals in thin section and to interpret geologic histories.
Why do we do petrographic analysis?
The information from a petrographic analysis is most commonly used to uncover performance issues or degradation mechanisms and the extent of damage, though it can also be used to verify mix design.
What is petrographic test of aggregate?
What is petrographic study?
Petrography is the study of rocks in thin section by means of a petrographic microscope (i.e., an instrument that employs polarized light that vibrates in a single plane). Petrography is primarily concerned with the systematic classification and precise description of rocks.
What is a petrographic examination?
Petrographic testing is the use of microscopes to examine samples of rock or concrete to determine their mineralogical and chemical characteristics. Samples for petrographic examination can be taken from lump samples or cores. They are impregnated with resin.
What is petrographic analysis used for?
Petrographic analysis identifies the origin, whether igneous, sedimentary, or metamorphic, and the mineral content for the classification of a rock.
How do you identify heavy minerals in the thin section?
The transparent heavy minerals can be determined by an experienced petrographer using the point counter analysis in thin section dispersed sample. The translucent or even completely opaque heavy minerals, however, can only be determined in polished thin or thick section using a reflected light polarization microscope.
How can you identify a tourmaline in a thin section?
Tourmaline thin section
- Formula: (Na,Ca)(Mg,Li,Al,Fe2+)3Al6 (BO3)3Si6O18(OH)4
- System: Trigonal.
- Color: Pale brown to dark-brown to brownish-black, also dark-yellow, blue.
- Lustre: Vitreous, Resinous.
- Hardness: 7.
- Density: 2.9–3.1.
What is petrographic analysis of coal?
Coal petrography is a microscopic technique used to determine a coal’s rank (degree of coalification) and type (amount and category of macerals). Producers and users of coal and coke rely on SGS, an industry leader in coal petrology, for independent, globally recognised coal petrographic analysis.