The crossword solution for the term OPAL OR 'COAL' ENDING is ESCE. Opal is a mineraloid composed of hydrated amorphous silica, and is a form of precious opal. It is found in many colors, including white, yellow, orange, red, blue, green, pink, and black. Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. It is composed primarily of carbon, along with variable quantities of other elements, such as hydrogen, sulfur, oxygen, and nitrogen. The ending ESCE is a common suffix used to form nouns from verbs.