Spessartine in rhyolites in Colorado and Maine. In Madagascar, spessartines are exploited either in their bedrock or in alluvium. The orange garnets result from sodium-rich pegmatites. Spessartines are found in bedrock in the highlands in the Sahatany valley. Those in alluvium are generally found in southern Madagascar or in the Maevatanana region. Spessartine forms a solid solution series with the garnet species almandine. Well-formed crystals from this series, varying in color from very dark-red to bright yellow-orange, were found in Latinka, Rhodope Mountains, Kardzhali Province, Bulgaria. Spessartine, like the other garnets, always occurs as a blend with other species. Gems with
Gemstone the stone such as color zoning (the uneven distribution of coloring within a gem) and asteria (star effects). The Greeks, for example, greatly valued asteria gemstones, which were regarded as powerful love charms, and Helen of Troy was known to have worn star-corundum. Aside from the diamond, the ruby, sapphire, emerald, pearl (not, strictly speaking, a gemstone), and opal have also been considered to be precious. Up to the discoveries of bulk amethyst in Brazil in the 19th century, amethyst was considered a "precious stone" as well, going back to ancient Greece. Even in the last century certain stones such