I'm not sure how you figured the specific gravity but first you weigh the sample in air. Then weight the sample in a container of water. To do this, you need a set of scales that allows a sample holder to attach to the bottom of the scales in order to weigh it in water.
Bulk Specific Gravity = A/B-C
Where:
A = mass, in grams, of sample in air.
B = mass, in grams, of surface dry specimen in air.
C = mass, in grams, of sample in water.
I once was at an auction where the great grandaddy had supposedly seen a meteor hit the ground and it was being auctioned off with other family heirlooms. The "rock" weighed about a hundred pounds. As I was examining it, I noticed that it had some native rock stuck to it. Someone else asked me what I thought. I told them that I was a geologist and I didn't think it was a meteorite. The next thing I know, a woman was sticking a phone in my face saying "talk to my boss." It was a lawyer from a nearby town who had sent her to bid on the rock. I told him that I thought that it was secondary hematite and not a meteorite. I had about ten people leaning towards me, listening in. It sold for $200.
