Highfield Resources Ltd. said resources at the Muga potash project in Spain increased to 234.75 million tonnes grading 12.28% potassium oxide in the combined measured and indicated categories.

Inferred resource stood at 32.6 million tonnes grading 12.92% potassium oxide, or K2O, for total resource of 267.4 million tonnes grading 12.36% K2O.

In November 2015, the Australia-listed explorer outlined a total measured, indicated and inferred resource of 263.7 million tonnes grading 13.50% K2O, with 224.6 million tonnes grading 13.40% K2O in the higher-confidence measured and indicated categories.

The reduction in grade was due to using a lower cutoff grade of 8% overall K2O instead of 8% K2O in sylvinite. Assays from two additional drill holes in the center of the deposit were incorporated in the updated resource estimate.

A new ore reserve statement, based on the updated resource estimate, is due later this quarter.