A leading Brazilian agricultural producer has bought 3,250 tons of the product following a smaller purchase of 198 tons in 2017 - that's 15 times' larger than last year.
"It is gratifying to see a return costumer placing any order," president and chief executive of Verde Cristiano Veloso told investors.
"It is even more pleasing to see a significantly enlarged second order.
"This growth in demand for Super Greensand is what we expect from the market, both from famers that run a trial over a harvest period and from farmers that learn about prior success from neighboring farms".
The company noted that the price per ton of Super Greensand was higher than the reference used in its pre-feasibility study, announced in 2017.
The company said this reflected the increase in potash prices in global markets.
Verde noted it had started its relationship with this buyer in 2014 to supply the potash needs across its plantations.
The buyer was kept abreast of the firm's many field tests with Super Greensand.
Super Greensand contains 68 minerals and trace elements, including potassium, iron, magnesium and manganese.
A pre-feasibility study of the deposit from where it hails - the Cerrado Verde project - showed a net present value of US$1.98bn and internal rate of return (IRR) of 290%.
The study considers exponential growth in production, with phase 1 production capacity of 0.6 Mtpy (million tonnes per year), with phase 2 production capacity of 5 Mtpy (million tonnes per year).
Phase 3 production capacity will be 25 Mtpy (million tonnes per year).
Verde is currently building its own production plant, to enter into operations in the second half of 2018. It will have capacity for around 0.3 Mtpy (45 tons per hour) at a cost of around US$500,000.
Shares added 5.06% in Toronto to C$0.83.