How do you find specific gravity of Iron ore?

Specific gravity is equal to the density of the iron ore divided by the density of water. The densities change with temperature, so I will assume a temperature of 4 degrees C for this calculation. At this temperature the density of water is 1000kg/m^3. There are various types of iron ore with varying densities. I found a reference table that states the density if iron ore ranges from 2100 to 2900kg/m^3. I will use the average: 2400kg/m^3. The reference table doesn't give a temperature, but oh well. I would choose 4 degrees C if I could. This gives us:

specific gravity=(2400kg/m^3)/(1000kg/m^3)

=2.4

Notice there are no units. This is a dimensionless parameter. It says iron is 2.4 times as dense as water. It will sink.