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Introduction of Slate

Slate was formed in Neoproterozoic (630 million years ago, the variation range of CIA value was between 48 and 61. However, there was a sudden change, it became between 60 to 71. Underwent a cold event, ended with warm environment.) Composition of Slate: more than 50% quartzite, about 20% clay, about 13% goethite and more than 10% other materials. In the composition of slate, there are many detrital minerals (such as quartzite, feldspar, mica and etc.) and authigenic minerals (such as oxide and hydrogen of iron, aluminum and manganese). Green and low radioactivity: slate belongs to class A building materials (radioactive element 60 baker/per square meter). In China, before establishing the radioactive standards, human’s health had been taken into consideration. Under the control of total radioactive amount 1mSv, deducting the radioactivity of nature and other materials, class A, B and C building materials had been classified. International Commission on Radiological Protection stipulates the standard of 100 baker/per square meter, which is decided by the radiation caused by radon gas. And class A stipulates 70 baker/per square meter. Hence, in 2008, slate won the bid among more than 100 stone materials in bidding of ground projects of National Stadium (Bird Nest). Collection value: slate is colorful with diversity of patterns, which make it have ornamental value. In addition, there is no identical slate. And it is totally different between different kinds of slate. All of these made the slate unique. (Test Report as Attached)