Colluli Drilling Intersects Shallowest Ever Potash Deposit

Development News Video

South Boulder Mines’ Colluli Potash deposit in Eritrea is not only the world’s shallowest potash deposit but the world’s first, modern, open pit potash mine

World's shallowest evaporite potash deposit is now in Eritrea, only at 1.25 meter from the surface
World’s shallowest evaporite potash deposit is now in Eritrea, only at 1.25 meter from the surface

By Proactive Investor,

South Boulder Mines (ASX:STB) has intersected the shallowest potash deposits of 1.25 metres at 38.88% KCl (potassium chloride) at the Colluli Area A resource in Eritrea following shallow drilling through the Sylvinite mineralisation layer.

The 14 metallurgical drill hole program was designed to obtain samples to complete the processing test work for the Colluli definitive feasibility study.

The data will also be used to provide geotechnical data and orebody geometry to optimise the open pit mining plans and update the resource categories of the Colluli potash deposit. 

The drill holes were located in the Area A deposit within the existing JORC compliant Mineral Resource Estimate.

The large diameter diamond drilling program confirmed the continuity of the Sylvinite mineralization within the deposit and also intersected zones of high grade mineralisation not previously encountered in earlier drilling.

The best intersections included 3.70 metres of Sylvinite at 28.96% KCl from 43.92 metres including 1.82 metres at 40.79% KCl; 5.90 metres at 34.30% KCl from 39.10 metres including 3.89 metres at 42.20% KCl from 41.11 metres; 3.42 metres at 38.54%KCl from 35.77 metres and 5 metres at 34.24% KCl from 57.32 metres, among others.

The drilling results represent the first Sylvinite mineralisation detected less than 30 metres from the surface, while previous best results returned 30% KCl from Sylvinite at 33 metres depth.


South Boulder is working towards developing the world’s first, modern, open pit potash mine, with initial production scheduled for 2016 or sooner.

The Colluli Potash Project hosts a total JORC resource of 1.08 billion tonnes at 17.97% KCl or 11.35% K2O for total contained potash of 194 million tonnes KCl or 123 million tonnes K2O.

This includes higher grade sylvinite of 114.6 million tonnes at 28.56% KCl or 18.04% K2O.

The current resource is included in an exploration target of 1.25 to 1.75 billion tonnes at 18% to 20% KCl.

A definitive feasibility study that started in April 2012 is currently underway.


The 14 hole metallurgical drilling has returned the shallowest potash deposit to date at South Boulder Mines‘ Colluli Area A resource, with mineralisation detected at less than 30 metres from the surface.

This shallow depth provides further operating and start up costs benefits at the flagship project.

South Boulder also recently completed the demerger of its non-potash assets to Duketon Mining that would allow it to focus on the Colluli project.

It remains well funded for future activity at Colluli with a cash balance of $14.8 million.