Рубин__

Rubin - a mineral belonging to the corundum class, with a triangular crystal structure and a hardness of 9. It is named after the Latin word 'rubens' or 'rubinus', meaning 'red'. Rubin is a variety of aluminum oxide (Al2O3). An older name for rubin is 'lal' or 'red jade'. The density of rubin ranges from 3.97 to 4.05 g/cm3. Wikipedia provides detailed information about rubin at ru.wikipedia.org/wiki/Рубин. A saved copy of the Wikipedia page can be accessed at hghltd.yandex.net/yandbtm?url=website%3Fref%3Dhttp%253A%252F%252Fru.wikipedia.org%252Fwiki