Depending on the chemical composition the structural parameters of the melilite vary in the range between gehlenite and mernite.Melilitic separation and melilite as a primary phase are very rare.

黄长石的结构参数，按其化学成分是在钙铝黄长石和镁黄长石之间变化，黄长石作为原始矿物相在碱性矿渣中比较罕见。