Indian women for ages have been using kaajal as eye liner without knowing that it is a product of high technology. Now scientists are talking about commercialising the process.
Scientists at the Indian Institute of Technology in Kanpur have shown that kaajal actually contains carbon nanotubes (CNTs).
A group of researchers in France showed that lead-based chemistry, which was initiated in Egypt more than 4000 years ago, could result in the synthesis of lead sulfide (PbS, galena) nanocrystals. With a diameter of about 5 nm, the appearance of these crystals is quite similar to PbS quantum dots synthesized by modern materials science techniques.
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Update (30 September 2006): Scientific American has a story with some more details (and a couple of pictures) on the ancient hair-dye:
... [T]he strands [which were soaked in the Greco-Roman formula] were shot through with lead-sulfide crystals averaging 4.8 nanometers in size--about the same as the so-called quantum dots studied by researchers today. The crystals formed strings down the length of the hair fiber. Judging from the spacing of these strings and chemical changes to the hair, the crystals apparently grow among the sulfur-rich amino acids that surround the hair's keratin microfibers ...