I am trying to make my own SG balance. Need this to handle rocks say smaller than a football. End result is to identify nephrite from grossular garnet, chert and serpentine without cutting or polishing a window on the piece. Where I have been collecting some rocks are not that different looking due to iron staining.

So built prototype out of wood. Its beam is about 4 ft and the rock is lowered in to a 5 gal bucket with water in it, just to give you an idea what it looks like.

1) should the container I put the rock in to measure in air hang directly from center of the balance beam

2) tested a piece of BC jade and came up with SG of 3.3 book says 2.9 to 3.03 so I need to fine tune this a little. I did find a reference that said SG could be as high as 3.3 for nephrite. Whose charts/info do you believe?

3) any hints on how to make this more accurate?

Thanks Mike

From Mike C - June 21, 2009 at 13:26:13

Message: 67947