Mineral resource classification is the classification of mineral deposits based on their geologic certainty and economic value.
Here's a list of the top 10 most expensive cities in the country, ranked by average monthly rent for a single person: 1. San Francisco, $2,077. 2. New York City, $1,994. 3. Boston, $1,721. 4. Washington, D.C., $1,397. 5. Seattle, $1,288.
Image caption Singapore has been moving up the ranks of the world's most expensive cities to live in over the last decade. Singapore has topped 131 cities globally to become the world's most expensive city to live in 2014, according to the Economist Intelligence Unit (EIU).