(April 2015) Corruption in Brazil exists on all levels of society from the top echelons of political power (as seen in the MensalÃ£o Scandal and the Operation Car Wash and the Petrobras scandals) to the smallest municipalities.
Quartz sands, which are high in silica content, are used to make glass. When quartz sands are crushed they produce particles with sharp, angular edges that are sometimes used to make sandpaper for smoothing wood. Some quartz sand is found in the form of sandstone.
Foundry Sand Types. According to the different binders, foundry sand used for moulding can be divided into green sand, water glass sand and resin sand. Green Sand (Clay Sand) Clay sand is the mixture of natural silica sand, clay, additives and water.The clay used to make wet clay sand is bentonite clay. The compressive strength is generally 0.05 to 0.1 Mpa.reen Sand (Clay Sand) Clay sand is the mixture of natural silica sand, clay, additives and water. The clay used to make wet clay sand is bentonite clay. The compressive strength is generally 0.05 to 0.1 Mpa.