Mr. Obama rarely plays with other politicians - though he has played 7 times with Vice President Biden. In a fence-mending gesture, Mr. Obama invited then-House Speaker John Boehner to play on one occasion in June 2011 along with Gov. John Kasich, both Ohio Republicans.
Here are some ways to classify coal (by grouping it with similar types of rocks): Because slag formed from lava-like melted rock, it's sort of like an igneous rock -- but because humans made the melt, it's not a true igneous rock. So, we made up a new classification for slag: We call it a pseudo-igneous rock (pronounced SUE-doe ig-NEE-us).
This is because when coal is burned it releases a chemical known as, C02 (carbon dioxide). This is the main cause of global warming. In addition, in order to get to the coal deep inside the earth, deep shafts are built which can affect groundwater and surface water. Fun Facts About Coal ~ Did You Knowâ¦...coal has to be quite dry before it will burn?