Poudretteite (Credit: Smithsonian Gem Collection)
Poudretteite (KNa2B3Si12O30) was originally discovered in Mont St. Hilaire Quebec, Canada in the 1960s by the Poudrette family. The gem is naturally pink in color and has a Mohs hardness of 5. It wasn’t until 2000 until the first gem quality poudretteite was found in Mogok, Burma at an amazing 9.41 carats (pictured above).
Black Opal (Credit: Bonhams Ltd)
Fire Opal (SiO2·nH2O) is actually not technically a mineral but instead is a mineraloid. The reason being opal does not have a crystal structure that is required for all minerals. As noted in the chemical formula, opal is a hydrated form of silica or silicon dioxide. Opals can form in a variety of different colors depending on the environmental conditions during formation. The mineralogy of opal allows it to diffract light, causing it to shimmer various colors.
Jeremejevite (Credit: Gem Rock Auctions)
Jeremejevite (Al6B5O15(F,OH)3) is an aluminum bearing borate mineral with associated fluoride and hydroxide. It was first found in the Adun-Chilon Mountains in Siberia in 1883. This gem has a similar hardness as quartz, 6.5 to 7.5 on the Mohs scale, and therefore is ideal for jewelry making.