Corundum (var: Sapphire) (Bi-color Twin) Bolivia metallic compressed rhombohedra of chocolate brown

compressed rhombohedra of chocolate brown (nearly black) Siderite on matrix

Specimen #PREH31115

This piece showcases the largest colorless to white Calcite rhombehedra that I have seen from this locality with excellent

This is one of the very few specimens of Franckeite that I have seen from the famous Siglo XX mine

form and top-notch crystallization

Corundum (var: Sapphire) (Bi-color Twin) Bolivia metallic compressed rhombohedra of chocolate brownGood Sapphire crystals are hard to find, twins are even more rare, but finding true bicolor twins is off the charts. Now I say true bicolor twins, because I dont really count a twinned crystal with varying degrees of blue as being multicolored necessarily. Theres no mistake with this piece as the color contrasting is about a defined as it gets for Sapphire. Ive seen twinned Sapphires with blue and yellow hues in the same crystal, but I dont know if I