Hello all…

My daughter collected some salt rocks from a salt bed. They are in large crystals but have dirt mixed in. See this picture at the bottom of the post.

What are my best options for separating the dirt from the salt? I know I can dissolve the rock in hot water, filter thorough a coffee filter (hopefully catching the dirt?) and then boil away the water.

Are there better options? Any way to retain the large rocks/crystals while getting rid of a good portion of the dirt?

With the hope that the dirt is embedded only on the surface, you might try wahing one or two, but be prepared to lose significant size. Or, set them out as a salt lick and let the critters do the work.

What are you trying to accomplish here? Have a lump of salt as a decoration or to try to refine the salt to use?

Wire brush?

Not sure what the aim is.

If you go the route of dissolving the salt in water, with the hope/intent of getting salt that would be safe to consume, be aware that while 'dirt' may not be soluble, bacteria and other contaminants may wind up in the water/brine.

If the crystal's intact and the dirt is just on the surface, maybe gentle use of a soft paintbrush to dislodge the dirt from the salt?

My 9 year old just wants to try and clean them up so it looks like big hunk of salt… not a big hunk of dirty salt. We aren’t intending on consuming it in any way. If we did, though, wouldn’t boiling off the water also kill any bacteria that was present?

Again, not the intent, just a thought.

We’ll try a toothbrush and see what happens first.

quote:

Originally posted by thumperfbc:
My 9 year old just wants to try and clean them up so it looks like big hunk of salt… not a big hunk of dirty salt. We aren’t intending on consuming it in any way. If we did, though, wouldn’t boiling off the water also kill any bacteria that was present?

Again, not the intent, just a thought.

We’ll try a toothbrush and see what happens first.

To answer the bacterial question, some types of spore producing bacilli can survive boiling (at least the spores do).

For the cleaning, how about a dental pick and an old toothbrush?

There is also the beauty of enjoying the salt rocks with the dirt ... as it shows they came from the earth.

Maybe something like silly putty? The idea being something that would stick to the dirt and remain cohesive enough that you could pull it away and have the dirt come with it.

So, salt is soluble in water. If you put this in a pot and boil it your end result will be dirty boiling salt water. If you ran the dirty salt water through a filter the dirt and some salt might be captured. If you caught the filtered salt water and allowed it to evaporate, the salt crystals would reform BUT the "rock" shape would be lost.

Said all of that to say, it might be a fun "science" experiment for your daughter. Teaching her that a solid can be turned into a liquid mixture and back to a solid.

The only way you could "boil" away the dirt might be to use a clothing steamer and wipe once a small area has liquified. Then you're dealing with potential steam burns and still changing the shape of the rock.

Don't set it on wood furniture or you will get damage. Keep it in or on plastic. To totally preserve it would require an air tight container.

edited to add
Maybe you already knew all of this. Someone didn't and now they do.

Alcohol won't dissolve salt. I use 99% rubbing alcohol, with table salt as a mild abrasive, when cleaning glassware.

Dental drill. Pretend the dirt’s a cavity and grind it out of there.