Boracite- a magnesium borate mineral with formula: Mg3B7O13Cl. It occurs as blue green, colorless, gray, yellow to white crystals in the orthorhombic - pyramidal crystal system. Boracite also shows pseudo-isometric cubical and octahedral forms. These are thought to be the result of transition from an unstable high temperature isometric form on cooling. Penetration twins are not unusual.
VERY RARE specimen featuring Acanthite crystals nestled between Amethyst points! Someone told me years ago that no Silver minerals appear in crystal form with Amethyst from the Creede localty, but this was obviously incorrect. I will admit I haven’t seen too many of them over the years and this is definately the best specimen I’ve come across. The Acanthite crystals are fairly distinct with a slight secondary growth along some crystal faces.