QUOTE (tanjent @ Nov 30 2018, 07:08 PM)
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Isn't that how panning for gold works? If you put heterogeneous gravel in a pan and agitate it, the smaller particles will settle to the bottom and the larger chunks will "float" to the top, even if they are intrinsically denser, because their irregular shapes prevent them from packing together as tightly.
Actually, what you're describing is "the Brasil Nut Effect" and there's even a paper on this
"The spherical Brazil Nut Effect and its significance to asteroids"
https://academic.oup.com/mnras/article-pdf/...556/stu1388.pdfPanning for gold is kinda the opposite, based on bulk density rather than grain size. Since gold is denser than stone, it is retained in the pan, or settles out into the grooves of a sluice, or if you're really old-school, settles out in the wool of a sheepskin...