Hendrik is correct that in the magnesium chloride powder the 2% impurities are other powdered trace chemicals and not water. The manufacturer can provide the impurity information to you. However, after the container has been opened, it will absorb water from the air. The amount of water in your powder sample will depend upon the exposure to air, the humidity of that air and how hygroscopic the powder is. You should be able to find information on the internet or in chemical tables to give you an idea of how much water the powder can/will absorb per gram. If it is critical for you to know exactly how much moisture is in your particular sample, you may just have to measure it. Typical procedure if you need to control water content is to use freshly opened containers so that you know it is dry or to dry the powder by forced evaporation or moisture absorbers before use.

Hi Eddie

I am posting your private mail to me here so CR4's can help

"A nonprofitable company in the Sudan by the Red Sea is importing mgcl 98% pure to mix in a paste that includes fiber glass mgo + agricultural left overs to form panels and manufacture low cost prefabricated housing for poor and refugees including Darfor region . purchasing by hard currency + transport + custom and VAT makes their production very expensive and not practical. that is why they came up with this idea of producing mg cl locally , mean while I in New York don't know any thing about chemistry, was asked to help. I did not know how to deal with computers or search engines or not even how to write my name in it, but I 'll say I came along way to write you this message after finding out about CR4 and other things that I am still learning, like silico thermic plants and others.so I was able to contact a couple of manufacturers overseas(cheap) to find a way to produce the magnesium from sea water and their main questions were the initial and final moisture?

Hendrik, it took me three month of 10 hours a day on the computers to get to where I am today .so as you may have gathered by now I am not technical or bright guy.can you help me to help this company to get what they need ,in the most economical way possible please? thanks."

What you actually are asking in this post is the concentration of salts in the ocean next to Sudan. right?

What you really want to know is how to produce Mg Cl2 cheaply.

1) MgCO3 is a mineral also found in abundance in dolomitic areas. (I have some lying in my garden). If treated with HCL the result is

MgCl2 + CO2 + H2O. Unfortunately some ZnCO3 is also present.

2) In Namibia with sea water & in SA (pumped from below the surface where an ancient inland ocean left large deposits) the water is pumped into flat evaporation ponds. the water is allowed to evaporate and the salt is gathered with shovels. The concentration is about 90% sodium chloride, 9% MgCl2 and 1% other. (fat guess)

Can somebody suggest another combination of Sudan material for building houses?