The Nelson clay deposit occurs on the banks of Graham Narrows near the airfield in Nelson and covers an area up to 1 kilometre long.

Limited deposits of silty clay, close to lake level, occur in the vicinity of Nelson. The clay has been used in the past for the manufacture of common brick but no production figures are available. The clay may have originated as lake or glacial deposits.

The clay forms a mass of good plasticity with 28 per cent water and an air shrinkage of five per cent. When wet-moulded the clay burned to a hard, not very dense, brick of red color. The clay is past vitrification at cone 1 and fuses at cone 3.