Translations:Adventist Youth Honors Answer Book/Nature/Rocks & Minerals/27/en

But what use is specific gravity? It helps us identify a mineral. We can measure a sample's specific gravity and compare it to the specific gravities of known specimens. To do this, we will need to make two measurements: the weight of the specimen, and its volume. Weight is easy (assuming you have a scale or a balance that can measure grams), but how do you measure the volume of an irregularly shaped specimen? All you need is some water, a drop of dish soap, and a graduated cylinder marked in metric units (note that 1 milliliter equals 1 cubic centimeter). Put some water in the cylinder, adding enough until the level comes to a convenient, well-marked level (such as 100 ml). Add a drop of dish soap to break the surface tension (you won't need more than a tiny drop). Then drop the specimen into the water and note the new water level. Subtracting the new level from the old will give you the volume of the specimen. Now all you need to do is divide the weight in grams by the volume in milliliters.