The Helmholtz coil system of the MOLSPIN anisotropy delineator is shown to be partly sensitive to the specimen shape, particularly if the sample departs from the optimum shape. The effect is found to be most marked when measuring weakly anisotropic rocks which have an anisotropy below about 13 × 10−12 m3 and susceptibility less than 50 × 10−10 m3. However, comparison of MOLSPIN data to measurements undertaken on low and high field torque magnetometers, suggest the results are not unduly affected by sample shape if the rock anisotropy signal is sufficient to dominate this spurious effect. Some suggestions are also made for minimising noise factors and thus improving instrument sensitivity.
SUMMARY The computer-based system for the curation of igneous, metamorphic and sedimentary rocks (ROCKFILE) is designed to cater for collections that are, at least in part, highly mobile, such as those used for teaching. Its provisions include easy logging and editing of specimen records, listing of catalogues and rapid machine searching of the databases for specimens that satisfy specific criteria; this last facility eliminates the need for complex cross-referencing. In addition, it allows for the recording of geological as well as managerial information, a high degree of security, a unique specimen numbering system and multiple storage locations that are independent from the specimen numbers.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
'/%3e%3cuse xlink:href='%23a' transform='rotate(144 450 300)'/%3e%3cuse xlink:href='%23a' transform='rotate(216 450 300)'/%3e%3cuse xlink:href='%23a' transform='rotate(288 450 300)'/%3e%3c/svg%3e)