SELENITE DEPOSIT

Press, Volume CI, Issue 29742, 8 February 1962, Page 12

SELENITE DEPOSIT

Huge Crystals 17- 'j Large selenite crystals up to Ift long. 2in to 3in wide, and lin thick have been found by Messrs H. S. Gair and E. T. An near, of the Geological Survey, Department of Scientific and Industrial Research, Christchurch, in the Upper Hakataramea valley. “The biggest I had seen previously were about lin to 2in long, and most are more of the size of a finger-nail,” said Mr Gair. The crystals in the Hakataramea deposit were in ancient clays, and were mostly arranged like the spokes of a wheel in the horizontal geological plane of the stratum. The;)' are believed to have been formed about 70 million years ago. Selenite is a crystalline variety of the mineral gypsum (anhydrous calcium sulphate). It is known to form under a warm climate during the drying up of a cut-off arm of the sea, or alternatively as the result of the action of sulphuric acid on shell material. In the same stratum as that in which the Hakataramea crystals were found, there were casts of ancient shells.

Although calcium sulphate has many industrial uses, Mr Gair does not believe the new find is likely to be of economic importance, as gypsum is found in large quantities in easily accessible deposits in many parts of the world. Digging out the Hakataramea crystals involved the removal of a good deal of clay for each “wheel” excavated.