NMR imaging of 1H in hydrous minerals

NMR (Nuclear Magnetic Resonance) of H-1 is applied for the first time to the three-dimensional imaging of hydrogen-bearing samples (stilbite, agate, and enhydros) from geothermal fields. The spin-spin relaxation time of the nuclei of H-1 in hydrous minerals is very short, so that it has been difficult to detect NMR signals with a high S/N ratio. This technical problem has been solved by newly developed probeheads and pulse sequences, so that clear images of H-1 in stilbite, agate, and enhydros can now be obtained. For example, H-1 in an enhydros sample (about 5 cm in diameter) is successfully imaged at a resolution of 0.31 mm, NMR imaging is nondestructive and automatic and is therefore a promising instrument for the rapid acquisition of data on the three-dimensional distribution of water and hydrous minerals in rock samples from geothermal fields. (C) 1998 CNR. Published by Elsevier Science Ltd. All rights reserved.