EFFECT OF CHEMISTRY ON CALCITE LATTICE SPACING: IMPLICATIONS FOR FLUORESCENCE AND ORE GENESIS

CALCITE, THE PREDOMINANT COUNTRY ROCK MINERAL IN THE STERLING HILL ORE DEPOSIT, IS FREQUENTLY FLUORESCENT DUE TO THE MINERAL'S INCORPORATION OF MANGANESE INTO THE CRYSTAL LATTICE. X-RAY DIFFRACTION OF CALCITE IN THE ORE DEPOSIT SHOWED AN INCREASING SHIFT IN PRIMARY PEAK POSITION FROM THE IDEAL PLACE AT 29.3 DEGREES TWO THETA WITH INCREASING MANGANESE CONCENTRATION IN THE CALCITE.

X-RAY DIFFRACTION OF CALCITES CONTAINING REE'S ALSO SHOWED A SHIFT IN THE CALCITE'S PRIMARY PEAK POSITION FROM IDEAL WITH INCREASING CONCENTRATIONS OF REE'S. THE FRACTIONATION OF REE'S IN CALCITES, HEAVY REE'S VERSUS LIGHT REE'S, HAS BEEN CORRELATED WITH DIFFERING MODES OF GENESIS (BELLANCA, ET AL., 1981).

BASED ON THESE INITIAL RESULTS, IT WOULD APPEAR THAT X-RAY DIFFRACTION, WHEN COUPLED WITH ATOMIC ABSORPTION OR INDUCTIVELY COUPLED PLASMA TO DETERMINE THE CHEMISTRY OF CALCITE, WILL BE AN EXCELLENT TOOL FOR PROVIDING INFORMATION ON MINERAL FLUORESCENCE AND GENESIS.

REFERENCE: BELLANCA, A., DISALVO, P., ET AL., 1981, RARE EARTH AND MINOR ELEMENT DISTRIBUTION AND PETROGRPHIC FEATURES OF FLUORITES AND ASSOCIATED MESOZOIC LIMESTONES OF NORTHWESTERN SICILY: CHEM. GEOL., V. 32, PP. 255-269.