Yellow Opal - 10 pounds*Locality: Tanzania *Requires 20 lbs of shipping space* Color: Yellow opal, as the name suggests, showcases hues ranging from pale yellow to deeper golden tones. The intensity of the yellow color can vary depending on the specimen. Hardness: Opal typically has a hardness of around 5. 5 to 6. 5 on the Mohs scale. This places it in the range of hardness similar to that of glass or a knife blade. However, opal is relatively fragile compared to other