They tend to be precious metals, often due to perceived rarity. The album gained notorious recognition and is a fan favorite despite its rarity. Other parameters are the rarity and the attractiveness. The value of coins depends on their rarity. It is often used as a symbol of fantasy or rarity. The rarity of direct strikes is attributed to chance. The rarity of mastic and the difficulty of its production make it expensive. Their very short lifetime compared to total stellar lifetime accounts for their rarity. The Champion rarity in particular is exclusive to the Champion units. "A true rarity" is what media called it. Shopkins are collected and valued based on their rarity. He was a philanthropist, a rarity amongst Ruhr industrial leaders. There were warnings about the increasing rarity of the emu. It was the first set to contain cards of the mythic rarity. The cost of rarity arises as follows.