CALCITE W/ QUARTZ - DARK GRAY - UNIQUE - NEW MEXICO - LARGE 3.0 LBS -7" X 4" Approx Dark gray calcite is a variety of the mineral calcite, appearing in a dark gray color due to impurities or the way light interacts with its crystalline structure; it is still composed of calcium carbonate (CaCO3) like all calcite, has a hardness of 3 on the Mohs scale, exhibits perfect rhombohedral cleavage, and is often found in sedimentary rocks like limestone and marble, where the dark gray color can be caused by inclusions of other minerals or organic matter; it is readily identifiable by its reaction with dilute acid, fizzing visibly when touched with vinegar. Key points about dark gray calcite: Color: Dark gray, sometimes with subtle variations depending on the impurities present. Composition: Calcium carbonate (CaCO3) Occurrence: Commonly found in limestone, marble, and other sedimentary rocks ** SEE VIDEO ( IF AVAILABLE ) FOR FULL EFFECTS ** ** WE HAVE MANY BEAUTIFUL MINERALSPECIMENS FROM THE USA AROUND THE GLOBE ** MOST ARE FROM OUR VARIOUS TRIPS ** ** SEE MY STORE ** ** OUR GOAL IS TO MAKE COLLECTING FUN AFFORDABLE FOR ALL WITH GREAT LOW PRICING ** ITEM # 174 Shipping Fees SHIPPING HANDLING SHIPPING YOUR ITEM SHOULD ARRIVE WITHIN 1-5 BUSINESS DAYS FOR DOMESTIC ORDERS. SHIPMENT IS FIRST CLASS MAIL - UNLESS OTHERWISE STATED. LOOK FOR A SHIPPING CONFIRMATION MAIL. ORDERS WILL BE SHIPPED TO ADDRESS ON FILE. RETURNS: FULL 30 DAY RETURN POLICY ~ BUYER PAYS RETURN SHIPPING ~ CONTACT US FOR ANY CONCERNS. SATISFACATION IS TOP PRIORITY