![]() ![]() In Guatemala, early cutting tools, weapons and carved items thought to have been used in ritual ceremonies, all made from obsidian, have been found that date back to 10,000 BCE. Stone age people found that the very sharp edges made excellent tools such as hide scrapers, knives, and arrowheads. With a Mohs hardness of 5 to 6 and a conchoidal fracture, obsidian shares all of the basic physical properties of glass and is be considered to be quite brittle however these features have made obsidian very important to man for centuries. Chemically, obsidian is the same as rhyolite.Ī closer look at the Velvet Peacock obsidian from Oregon. Composed mainly of silica combined with oxides of aluminum, iron, magnesium, calcium, sodium and potassium when this material solidifies very quickly and with no defined crystal structure, it is a form of volcanic glass or obsidian. ![]() After the earth has been opened, the mantle’s mineral rich magma begins to ooze and run out of the earth as lava. Eventually these gases blow the crack wide open, usually forming a volcano. When there is a crack in the earth’s crust and gas pressures beneath it build up, the liquid rock and gasses of the mantle push at the crack, often moving the landscape around it. Under the mantle is the outer core, basically molten metal and the center of our Earth is a pressurized mass of iron and nickel that does not have room to flow, so it vibrates and is called the inner core. Beneath the crust is the mantle composed of a very thick and sluggish, hot mineral soup. The outer layer where we live is the crust. ![]() Taking us back to elementary school, there are four main layers to our Earth. A chunk of rough black obsidian alongside a 6 pound, water polished piece. ![]()
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