Attention-deficit/hyperactivity disorder (6.8%) was the most prevalent parent-reported current diagnosis among children aged 3â17 years, followed by behavioral or conduct problems (3.5%), anxiety (3.0%), depression (2.1%), autism spectrum disorders (1.1%), and Tourette syndrome (0.2% among children aged 6â17 years).
Most natural diamonds are formed at high temperature and pressure at depths of 140 to 190 kilometers (87 to 118 mi) in the Earth's mantle. Carbon-containing minerals provide the carbon source, and the growth occurs over periods from 1 billion to 3.3 billion years (25% to 75% of the age of the Earth).
Carbon is found free in nature in three allotropic forms: amorphous, graphite, and diamond. Graphite is one of the softest known materials while diamond is one of the hardest. Carbon, as microscopic diamonds, is found in some meteorites.Natural diamonds are found in ancient volcanic pipes such as found in South Africa.Diamonds are also recovered from the ocean floor off the Cape of Good Hope.raphite is one of the softest known materials while diamond is one of the hardest. Carbon, as microscopic diamonds, is found in some meteorites. Natural diamonds are found in ancient volcanic pipes such as found in South Africa. Diamonds are also recovered from the ocean floor off the Cape of Good Hope.