BS EN 12407:2019 pdf free.Natural stone test methods -Petrographic examination.
A macroscopic description of the sample is undertaken at first. The macroscopic description may involve a visual inspection aided by a hand lens or a stereoscopic microscope. Then one or more thin sections prepared from the sample are examined using an optical polarized transmitted light microscope in order to give a microscopic description and modal analysis (volume proportions of mineral phases) of the sample; where appropriate an additional polished section shall be prepared. Modal analysis is the most accurate determination of quantitative mineralogical composition of natural stones. It attributes to each mineral phase a certain percentage (voL.%]. Modal analysis is obtained by point counting following a standard procedure on thin sections (at least 44 mm x 28 mm) or using Shvetsov’s diagrams (or any other similar diagrams commonly used by petrographers).To facilitate the identification of some minerals with similar colours or optical properties it might be necessary in many cases to use different techniques such as: selective mineral staining methods, optical cathodoluminescence, XRD, SEM-EDS or WDS microprobe. If required, these methods should be clearly stated in the working order referring to widely-referenced manuals, but taking into account that such additional techniques are not part of the petrographic analysis described in this standard.The section normally measures about 44 mm x 28 mm, but in the case of coarser grain size stones, larger dimensions may be used [e.g. 75 mm x 50 mm) or several sections of normal dimensions can be prepared. If the rock texture is anisotropic it is necessary to prepare at least two sections with different orientation with respect to the anisotropy (e.g parallel and perpendicular to anisotropy planes). By using the rock saw, several small blocks are cut of dimensions in the range ofat least +4-5cmx土3- 4 cm and thickness in the range of士3 to 4 mm thick. In case of porous samples pores are filled with Canada balsam (or any synthetic resin with approximately equivalent refractive index); the samples are then heated on the plate to approximately 100 °C and then cooled.BS EN 12407 pdf download.