| |
| | black sand |
 | | Black sand is a heavy, weakly magnetic, glossy, semi-metallic mixture of usually fine sands, found as part of a placer deposit. |
 | | Black sand concentrates often contain additional valuables, other than precious metals: rare earth elements, thorium, titanium, tungsten, zirconium and others are often fractionated during igneous magma processes into a common mineral-suite that later becomes fl sands, after weathering and erosion. |
 | | Several gemstones, such as garnet, ruby, sapphire, and diamond are found in placers and in the course of placer mining, and sands of these gems are found in fl sands and concentrates. |
| www.fact-library.com /black_sand.html (188 words) |
|