A bubble is a period of time in which a company or market returns to its pre-bubble level.
It can also be the case of a stock going public or a bond issue.
Coal is a commodity that has historically been very volatile.
According to the Bloomberg Billionaire Index, the market cap of the S&P 500 has dropped about 18% in the last 10 years.
At the same time, the price of coal has continued to decline.
In the meantime, the U. S. coal industry has struggled with a lack of production.
The decline in coal production and the high costs associated with coal mining have made the industry difficult to sustain.
According the U, coal mining is currently a bubble.
There are several reasons that coal mining companies have been struggling in recent years, according to The Hill.
One of the biggest problems is that the industry is in a state of collapse, as the price and supply of coal continues to decline, and the industry itself is facing a severe financial crisis.
The cost of mining coal is the biggest factor in the collapse of the coal industry.
The average cost of a pound of coal is currently about $2.20, according the Bureau of Labor Statistics.
However, the cost of producing coal is much higher.
Coal mining companies are currently paying a high price for producing coal.
According a report from Bloomberg, the average cost for a pound in the United States is $2,849.
This is a huge cost for miners, who are paying more than $40,000 a year to mine the commodity.
Other factors are a shortage of skilled workers, low rates of innovation and lower quality mining equipment, the report stated.
The price of mining is another factor that makes the coal mining industry in the U-S a bubble in the sense that it has a relatively high cost of production, as well as a very high price per ton of coal.
This means that mining companies can afford to pay less to make money.
However if the coal prices continue to drop, the costs for mining the commodity will continue to increase.
The collapse in the cost per ton could cause miners to go out of business, and could cause the price to drop.
Another reason for the decline in the price is the fact that the supply of the commodity has decreased dramatically.
According Bloomberg, there are currently about 7.6 billion tons of coal on the market, and there is only about one million tons left.
This leaves more than 3 million tons of the world’s supply in the ground.
If the price per pound of the U S coal goes down by 20%, that would mean that the remaining supply would be more than 7 million tons.
This would be a huge drop in the amount of coal that can be produced.
This drop in production would be the reason why the price will continue dropping, as a decrease in the supply would make the price go up.
The bottom line is that if the price drops by 20% and there are more than two million tons remaining in the earth, it would be catastrophic for the industry.