Yellow Calcite 10mm Round A Grade - 15-16 Inch bicone_beads It sometimes features dark brown

It sometimes features dark brown to black dendritic inclusions that branch like tiny tree limbs through the stone

orange and rust are due to traces of hematite within the stone

Ruby and Sapphire

Many stones in the Russian crown jewels from the 17th century which were thought to be rubies are actually red Tourmaline

As a Serpentine

Yellow Calcite 10mm Round A Grade - 15-16 Inch bicone_beads It sometimes features dark brownCalcite is a rock forming mineral that is extremely common and found throughout the world in sedimentary, metamorphic, and igneous rocks. Calcite is the principal constituent of limestone and marble. These rocks are extremely common and make up a significant portion of Earth's crust.