Like purple ribbons, blue ribbons represent many things, and among these are two types of cancer, colon cancer and colorectal cancer. Blue ribbons are also used, particularly in Canada, as a symbol for another issue that is related to cancer, anti-tobacco and anti-second-hand-smoke awareness. Light blue ribbons represent prostate cancer and, as an alternative to pink, childhood cancer. Gold is yet another alternative color for childhood cancer.
Oxygen is the most abundant element in rocks in Earth's crust, composing roughly 47 percent of the weight of all rock. The second most abundant element is silicon at 27 percent, followed by aluminum at 8 percent, iron at 5 percent, calcium at 4 percent, and sodium, potassium, and magnesium at about 2 percent each.eologists think the temperature of Earth's outer core is about 6,700 to 7,800 degrees F (3,700 to 4,300 degrees C), and the inner core may reach 12,600 degrees F (7,000 degrees C), hotter than the surface of the sun. Only the enormous pressures found at the super-hot inner core keep it solid.
Oxygen is the most abundant element on the Earth's surface (or crust). It comprises 49.5 percent of the total mass (amount) of the Earth's crust, waters, and atmosphere. Silicon is the second most abundant element. Silicon dioxide and silicates (salts derived from silicon dioxide) make up about 87 percent of the materials in the Earth's crust. (Source: Tzimopoulos, Nicholas D., et al. Modern Chemistry, pp. 289, 758.) However water is the most common substance on the surface of the Earth. In the atmosphere, Nitrogen is the most common element (78%). It is believed that the core of our planet is mostly made of iron (at very high pressure and density), so iron would be the most common element within the Earth.