Like other types of Calcite, the blue is comprised of calcium carbonate, with an addition of other minerals that cause its colour, its chemical formula is CaCO3 and it's a 3 on the mohs scale. 

Its calming blue colour means it's a good stone for the throat chakra, it's also suggested that it helps with anxiety and brings about peace and harmony.

wands are approx 9.5/10cm £18.95 
Hearts between 5 and 7cm and start at £18.95
Large Palmstone 7cm £14.95 
Sphere 8cm and is £36.95

Blue calcite