4 2 1 barotiya group of rocks the barotiya group of rocks of mesoproterozoic age include an assemblage of metasediments dominantly mica schist along with conglometrate meta arkose and.
Petrographic description of granite.
The thin sections were made by janwill petrograhics and the descriptions were completed by alana murphy.
He found the gold in small scales rarely exceeding a.
Petrographic examinations provide identification of types and varieties of rocks present in potential aggregates.
Included in this section is a list of applicable standards and test methods for granite descriptions and standards for related construction components fabrication tolerances standard finish descriptions geological and petrographic descriptions of granite physical and mechanical property requirements as well as descriptions of common repairs and reinforcements.
Three of the samples nl 32 nl 66 nl 74 all appear to be altered sedimentary rocks as.
Rocks under the microscope.
5 4 petrographic examination of aggregate considered for use in hydraulic cement concrete is one aspect of the evaluation of aggregate but petrographic examination is also used for many other purposes.
These are photomicrographs very thin slices of rock seen in plane polarised light or between crossed polarisers when the colours seen are produced by interference of light.
In this chapter petrographic characteristics of these rocks are explained in detail.
Merrill curator of the department of geology of the u.
These descriptions with photographs are included in appendix i.
The general process for writing rock descriptions is to start off with a general description general colour grain size texture followed by identification of the minerals within the rock the mineral assemblage the name of the rock deduced from the assemblage and then finally your best guess on how and where it was formed.
Some common rock types as seen under the microscope.
National museum washington upon an occurrence of free gold in granite describes an interesting instance of the dissemination of this noble metal in the substance of granite of normal composition believed to be from sonora mexico.
The classification of rocks is based on the information acquired during the petrographic analysis petrographic descriptions start with the field notes at the.
The petrographic descriptions of the rocks has helped in understanding the geology.
2014 079 1 this sample is a plutonic rock dominated by anhedral feldspar 60 percent and a lesser amount of quartz 40 percent.
Petrography is a branch of petrology that focuses on detailed descriptions of rocks someone who studies petrography is called a petrographer the mineral content and the textural relationships within the rock are described in detail.
