To: Diamond Daze who wrote (1306 ) 11/9/1997 8:23:00 PM From: Bill Jackson Read Replies (3) | Respond to
Chris; Ahah !, the thin edge of a wedge. When rock weathers away some goes very fine and blows away, far away, or is carried as silt in water. Some stays as gravel and wind/water movements gradually grind it away to smaller etc. The metals resist this as they are malleable and roll around and get squashed and monged into shapes that can be flat flakes or granules. As they are very heavy they do not move as far or as fast as the rock particles, so they fill in the low spots preferentially and among larger granules settle to the bottom, in general, especially in water deposits(placer) Water borne stuff does more settling as there are fluidizing aspects with water that air does not have due to the high density of water compared to air. (1000 cubic feet of air weighs 60 pounds, 1000 cubic feet of water weighs 60,000 pounds and of rock weighs 150,000 pounds and of gold weighs 1,200,000 pounds) So as rock and gold fall in moving water the gold falls faster and the gold much slower as the density differential is less. If you had styrofoam beads mixed with the gold and dirt the beads would even float, so does the dirt to a lesser gedree by falling slower. In air they are both more than 1000 times as dense and so fall at nearly the same rate ,(there is some segregation, but not like water, as the small light earth grains do blow far away, and some actually dissolve with bacteria and acid from natural rains. So you might lose 90% of the rock over time and 5% of the gold, and they will all blow together and fill valleys. You would expect stratification unless they all came from the same rock.
