Answer:
Sift the mixture to separate the rock from the iron filings, soil and salt.
You can then use a magnet to separate the iron filings from the salt and soil.
Afterwards, you can pour water into the remaining salt- soil mixture. Salt will dissolve but the soil will remain at the bottom of the water.
If you want to separate the salt from the water, you can boil it till all the water evaporates. The only thing that'd be left in the pan is salt.
