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.
The 20 most expensive cities in the world 2014: in pics. MORE... The website Expatistan.com collects information from almost 200,000 users around the world to calculate average prices in 1,600 cities for everyday items such as food, rent and petrol. Currently at number 20 is Washington DC. To see the 2015 updated version click here.