PURPOSE: To obtain a high concentration suspension of goethtite particles industrially, capable of without inducing disorder in the engaging and the slippage, and of preventing development of flaw due to the seizure during the hot pressing in processing a steel, etc.

CONSTITUTION: A high concentration aqueous suspension of goethite particles is obtained by after filtrating and washing with water of goethite particles with a spindle shape of which radius through the apsis of 1-0.1μm, produced by a wet reaction of a carbonic acid alkaline aqueous solution with a ferric chloride aqueous solution, by making a suspension of the goethite particles of which solid portion is 30-50wt.% by adding water, then by adjusting pH of the suspension in a range of 7.5-9.5, by adding phosphate compound of 0.5-1.0% in P conversion against the amount of the goethite particles in the suspension, and by mixing and agitating.