Halite                        Mineral Group: HALIDES   
aka Salt

Halite
  • we know halite as salt
  • Canada is the world's largest per capita consumers of salt because of our long roads, long winters and few people
  • translucent
  • vitreous luster

 


SPECIMEN ORIGIN: Windsor, Ontario CANADA
  • This massive, soft, peachy pink halite specimen is also called “rock salt”.
  • It feels slippery & greasy to the touch.
  • Salt dissolves easily in water and is formed by evaporation.
  • This piece has been carved into a candle holder.
     

SPECIMEN ORIGIN: Himalayas, PAKISTAN

Halite – Salt to you and me
© Bert Ellison 1999 - 2002

Chemically this compound is simple enough, being just sodium (a soft metal) and chlorine, a very unhealthy gas to form NaCl. Masses of it break into neat cubes (it’s isometric), soft at H2.5, average SG at 2.16 – and it tastes great!

Now that we’ve disposed of the dry facts, let’s look at other aspects of salt.

When we get ill we often get a saline drip. Why salt? It’s been suggested that the salt in our blood is a relic of our ancient born-in-the-sea heritage. And a proper balance of salt (and potassium) is still critical to our well being. We crave it and sometimes go to great lengths to get it. There are 3500 parts of salt in a million parts of average sea water – millions of tonnes – and vast amounts underground in fossil form but we can’t always get access to it. Yes, one can drink camels’ urine in desperation as has been done in the desert, but happily there are more pleasant ways to get salt.

In ancient, almost land-locked bays and lakes salt-bearing waters evaporated along with other salts like gypsum, anhydrite, sylvite and carnallite – the latter two being valuable potassium (K) salts. Beds hundreds of metres thick were later buried to form vast reserves of these minerals. Saskatchewan is a major supplier of potassium salts for fertilizer; it’s Devonian in age; southern Ontario is a great producer of salt from Silurian beds. Many hot countries draw salts into shallow ponds to evaporate seawater. In hot dry Iran "glaciers" of Cambrian salt have been squeezed to the surface by tectonic pressures because halite flows under pressure, like putty.

One of the most interesting aspects of salt is its appearance in salt domes, the most noteworthy being those around the Gulf of Mexico. Here are great beds of ancient salt, some as deep as 16,000 m (from seismic exploration). Somehow these become warped and initiate plastic flow, eventually forming towering "bubbles" – much like those seen in lava lamps. Since the SG of salt is less than that of the enclosing clay and sand beds, it tends to float upwards. In doing so these rising domes bend the overlying beds forming excellent traps and prolific oil and gas reservoirs. Some even reach near the surface where they are mined, not only for halite, but also vast amounts of sulphur which often cap these great "balloons".

In Roman times, the army was paid partly in salt and later the money allowance to buy their own salt appeared as salarium, from which we moderns – if we are fortunate enough – now draw our salaries.

Some of that salary may go to replace that rusting car in our garages, thanks to the ravages of road salt. On the plus side we get washing soda, baking soda, caustic soda, hydrochloric acid, bleaching powder, preservatives, flux, glass, glaze and soap.

Pass the salt, please!

 

 

 

 

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