The term SALT SOURCE can be broken down into three crossword solutions: MINE (4 letters), SEA (3 letters), and CELERY (6 letters). Salt is an essential mineral for human life, and it is found in many different sources. Mining is one of the most common ways to obtain salt, as it is often found in underground deposits. SEA salt is also a popular source, as it is obtained by evaporating seawater. Finally, CELERY is a vegetable that contains a high amount of sodium, which is a key component of salt.