The average cost of mercury is $12 to $14 per 100 grams. The cost varies depending on the quality and grade of mercury. For example, when mercury is bought for a plant in bulk, it costs 0.10 per gram and when purchased in bulk but if its high purity mercury, it may cost 40 to 50 cents per gram. If purity is not the criteria, then mercury can be got from a mercury thermometer which costs $14, giving a gram of mercury or so. The average scrape price of liquid mercury is about $5 per gallon. Mercury (Hg) is only one of the two elements that are liquid at room temperature. It is a very dangerous element. The liquid metal looks silver and is very dense. It alloys well with other elements and its vapor is poisonous. The element mercury is also called `quick silver’.