Rock Salt Vs. Sea Salt

Salt is such an essential to nearly every dish. A pinch can bring our the flavours of so many recipes. But when faced with so much choice to buy, which should you choose?

Salt is available from two main sources – underground mines, which give rock salt, and from evaporating off salt sea water leaving the crystals – sea salt. These salts have their differences, despite both having the same essential ingredient – sodium chloride, common salt.

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Knowing the difference between the two helps maximise these salts’ potential.

Rock salt vs sea salt: what’s the difference?

The main difference between rock salt and sea salt is where they are sourced. Rock salt is from underground mines; the salt is mined and is then processed.

Rock salt normally undergoes processing to remove any trace minerals. Then for most common salts, anti-caking agents and iodine are added. If iron is also added, it then becomes double-fortified salt. This is useful to protect against anaemia.

Sea salt is the product of evaporating seawater. It doesn’t undergo much processing; it only needs to evaporate the ocean water to get the salt content.

Because there isn’t much processing when extracting sea salt, it also has some trace minerals, which sometimes give its colour, and vitamins you not normally found in rock salt. Likewise, the slow formation of salt crystals as the water evaporates tends to give larger, more flaky crystals.

Rock salt vs sea salt: which is better?

Rock and sea salt are equally salty. Rock salt has the advantage of being more affordable, while sea salt generally has more flavour from trace vitamins and minerals.

I tend to make more of a distinction between processed table salts, which I use for cooking, and more flavoured salts which I use to finish a dish.

Rock salt vs sea salt: when to use them?

Common table salt is rock salt; the cheapest salt in the shops. However, both rock and sea salts can come in varieties with a higher price point. For everyday cooking, I use table salt.

Table salt normally has anti-caking agents added. This means that the container can sit in your cupboard and the salt won’t absorb water from the atmosphere and become a large, clumpy mess.

For things like salt crusts for baking fish or meat, where I’m using a lot of salt, there’s no need to spend any extra money. Go with table salt.

For finishing salt, i.e. salt added to a dish just before serving, this is where you can experiment with more interesting rock and sea salts.

Sea salt can make a great a finishing salt, adding some light crunch as well to your dishes. Should you wish, you can fine tune the flavours of the salt to the dish – for example, using a highly flavoured, mineralized salt with a strongly flavoured dish.

I like to add a large flaked salt, such as fleur de sel, to cooked meats. The little burst of saltiness from crunching into the flake… delicious!

Check to see if iodine has been added before using a salt in a dessert, such as a salted caramel. It can add a bitter flavour.

Can I use rock salt as a substitute for sea salt?

Rock salt and sea salt are generally interchangeable. However, take a little care if you are using a strongly flavoured salt to make sure it complements the dish.

I don’t think there’s much point in using expensive salts for salting water for vegetables or pasta. A packet of table salt is perfect for this.

Does rock salt taste the same as sea salt?

Some sea salts have a definite tang of the sea, from the trace minerals that remain in the salt as the sea water evaporates.

The other thing to be aware of is that a pinch of fine salt will have more salt in it than one of a much coarser salt. As always, taste and adjust, with the proviso that it’s easier to add than remove!

Is kosher salt rock salt or sea salt?

Kosher salt is pure sodium chloride, without any added clumping agents or (usually) iodine. It’s called kosher salt as it’s suitable for koshering, rather than having to be certified kosher.

Koshering is the process of removing blood from meat; one of the main ways of doing this is by salting the meat.

As a pure, unflavoured salt, kosher salt has become a staple in many professional kitchens, particularly in the USA. Also, the large flake size makes it easy to pick up a pinch.

If a recipe calls for kosher salt and you don’t have any, don’t fret – just use common table salt.

Is Himalayan salt a rock salt or sea salt?

All forms of Himalayan salt is rock salt, as it comes from salt mines in the Punjab region in the Himalayas. There are two variants of Himalayan salts: pink Himalayan, and black Himalayan salt.

Pink Himalayan salt gets its colour from from trace minerals, such as calcium, magnesium, and potassium. This salt variant has a mild salty and sweet flavour.

Another use of Himalayan salt is for cooking. A block of salt is heated in the oven and brough to the table. Salt retains heat well, remaining hot for hours.

To cook, place the food  – meat, fish or vegetables – straight onto the hot salt block.

This method works best when the food is cut small enough to cook quickly. During cooking, the food picks up a delicious saltiness. It makes for a great point of conversation.

As well as retaining heat, the block will also stay cold, so can be chilled to make an interesting serving dish for sushi. Or freeze it and use to serve ice cream!  

Black Himalayan salt or kala namak, meanwhile, gets its colour from chemical reactions during processing. It’s cooked in a kiln with spices and charcoal.

Because it’s cooked in high heat, and the charcoal creates a chemical reaction, the sodium chloride becomes sodium sulfide and hydrogen sulfide, which gives it its black and dark purple hue. This salt variant has this umami and almost rotten egg smell.

What is Fleur de sel?

Fleur de sel is a variant of sea salt that’s made ins shallow sea water pools, often along the Brittany region in France.

Fleur de sel is salt that forms on the surface of water in salt pans as the water evaporates, rather than at the bottom of the pan. The pyramid shaped salt flakes are very delicate, so must be harvested by hand.

Fleur de sel needs specific conditions to form – sunny, dry, and with slow, steady winds. Too much wind will disturb the water and the crystals won’t form.

All these factors make it an expensive form of salt.

Is table salt considered rock salt or sea salt?

Table salt is normally rock salt, as mined salt is a lot cheaper than sea salts. The salt is processed, with anti-caking agents added. Iodine is frequently added to supplement levels, and protect against iodine deficiency.

The thyroid need iodine for proper function, and using iodized salt is an easy way to make sure you’re receiveiving enough.

Celery and Garlic Salt

Theses are flavoured salts, where a base salt has been flavoured with either dried celery bulb powder, or garlic granules as appropriate.

They’re great for intensifying flavours in dishes, and celery salt is an essential for Bloody Mary and Virgin Mary cocktails.