I don't think fancy descriptions of where the nutrient is mined lend to credibility and allow them to up the price to consumers thinking it is special in some way. . Oils are typically not transdermal either. They are "organic" and "natural"but not likely to penetrate the skin enough. The magnesium is water soluble and hence the transdermal forms carry it chemically to the deep layers of the dermis where the blood vessels are.

One can only try the item and see if it works.Research on this topic remains scanty, still.

You can try Kirkman's cream...it has been around a long time...and even has a measuring scoop included. (100 mg per scoop)

Amazon.com: Kirkman Magnesium Sulfate Cream 4 oz Cream: Health & Personal Care
Or you can ask your doctor to order a compounded magnesium product made with a transdermal base.

The RX route most likely will cost more than Kirkman's.

I apply my lotion to my inner wrists and arms where the skin is thinnest and the veins show. In return it has lowered my high blood pressure so I don't need 3 drugs anymore. (only a small dose of one)

Aim for 200mg a day if you get a cream/lotion of quality that has a measuring device.

If you get a personally compounded one make sure the magnesium is ionic (chloride or sulfate). Magnesium hydroxide or oxide will not ionize in the blood to offer the magnesium to your tissues.

I know it is frustrating... but the topicals do work when you get one that crosses into the skin. Epsom salts work some, because the pore of the skip open in the warm water and the magnesium gets inside that way. Also staying in the salts for at least a 1/2 hr gives it time.