Gravity of Common Metals

Mica: 2.3

Feldspar: 2.5

Quartz: 2.7

Calcite: 2.7

Hornblende: 3.2

Garnet: 3.5

Topaz: 3.5

Corundum: 4.0

Magnetite: 5.2

Silver: 7.5

Lead: 11.3

Gold: 19.2

Gold is one of the heaviest elements there are. When gold is in its pure state, it has a density of about 19 and this means that it weighs around 19 times more the equal amount of water. When the gold is mixed or alloyed with other minerals, the density average will be under 19. As a result, precise gravity measurements can give a rough estimate of the purity of the gold. The average specific gravity of some of the most common minerals has been stated above.

Mica, Feldspar, Quartz, Calcite and Hornblende are the most common components of the sand and rocks that can be found and associated with gold. The low specific gravity is the reason these minerals wash away when they are panned. Magnetite is common of the magnetic black sand that is left at the bottom of a pan that is mixed with gold.

Corundum and topaz as well as garnet turn into the ruby sand that can at times also be found at the bottom of a pan. When they are formed in larger pieces, they are considered gem minerals. Corundum emerges as ruby or sapphire depending on the impurities there are in the stone. Topaz is a yellowish or amber gem and garnets are red just like ruby.

There are certain areas in which these minerals can be found in the same place as gold is found. Make sure to keep an open eye for any rock that is unusually heavy. You might run into the surprise of it being one of these minerals, a heavy rock could also be quartz with gold or silver within it.

Due to the fact that the specific gravity test is useful, there is a way to do this. Specific gravity can be found by separating the weight of the sample by the volume of the sample. The weight can be found in an easy way with the help of a scale or a balance. The volume can be easily found by a simple trick that was discovered by Archimedes.

The first thing you will need in order to make specific gravity measurements is a balance that can weigh the fractions of a gram. The balance also needs to be arranged so that you are able to weigh the sample in the usual way and when the sample is submerged in a small glass of water.

This needs to be done so that you can see how much lighter the sample seems to be when it is submerged in water. You know what it feels like to be in water; the water has a floating effect whenever one is swimming in the pool or the ocean and in some cases the floating effect is so much that you can actually float in the water. The degree in which the water lifts your body up is determined by your body’s specific gravity, in other words, your weight in relation to your actual size.

The way to see the specific gravity of a small gold nugget or a bag of gold dust etc, you first need to find out what its normal weight is and the weight it “losses” when it is placed in water. Finding out the normal weight can easily be done if you have a good scale that can read in grams and can weigh a nugget.

The way to get the supposed weight loss in the water, you will need to weigh your nugget one more time, however in this occasion you will need to put a container of water in front of the scales in some place where it will be fitting to hang the nugget in the water. You will probably need to tie one end of it with a little thread from the balance beams of the scale. What you need to be sure of is that you are weighing the nugget, the entire nugget and nothing else but the nugget.

After you have the weight of the nugget in the air and the weight of the nugget when it is submerged in water you will have what you need. The difference is the loss of weight in the water. These two numbers can then be put into an easy equation:

The sample weight in the air is equal to the specific gravity  

Loss of weight in the water

There are other ways of doing this; some are a little bit more precise, some are a little bit less precise, some are easier, and some are a bit more difficult. One of the simplest and least precise is the color scratch test. This test is based on the fact that the color of gold is different and varies depending on how pure the gold is.

There are shops that sell rocks that have what are known as “scratch kits” that consist of a color chart and shows the color for the different levels of gold purity. What you do is scratch the gold sample on a piece of sandpaper and compare the color of the scratch you made with the ones of the master chart. It is probably the easiest test of all but not the most reliable in our opinion.

There are other types of test that can be done on minerals to help you identify them. There are many people that are into collecting different minerals and rocks and it is considered a hobby for some. If you are interested in getting into this, we suggest doing a little research on it and getting some knowledge on mineralogy.