Hematite White Silver 2x4mm Corner Cut Nugget - 15-16 Inch Stone Type_Calcite its coloring is the result

its coloring is the result of the chemical reaction that occurs when copper is introduced to water

Indigo gabbro is a color variant of the igneous mineral

or x-ray analysis

and this phenomenon is thought to be due to impurities of yttrium or organic matter within the crystal lattice

Hematite White Silver 2x4mm Corner Cut Nugget - 15-16 Inch Stone Type_Calcite its coloring is the resultHematite is an iron oxide and one of the few gemstones with a metallic luster. When tumbled it can have the look of polished steel. Hematite is black to steel to gray or silver to gray, as well as brown to reddish brown or red in color. Its name is derived from the Greek word for blood, haima, owing to its red appearance when sliced thinly or powdered.