Vuagnatite is a mineral mainly consisting of oxygen (45.41%), calcium (22.75%), silicon (15.94%) and aluminum (15.32%), with traces of hydrogen (0.57%). It does not show radioactive properties. It widely occurs in
prehnite and in
hydrogrossular assemblages. It was first reported from an
ophiolite suite in
rodingite dikes. It has been described from rodingitised
gabbro, rodingites and
greywacke cobbles, and as veins in
serpentinite. Some of the recorded occurrences were in Japan, New Zealand, Turkey, Guatemala and California. It grows in small,
inclusion-free,
chemically pure isometric crystals up to a millimeter. The brown coloration is most probably caused by the high quantity of
iron oxide within the mineral, as darker specimens are rich in both titanium dioxide and iron oxide. Some of the crystals have small zones which seems to be continuous with the rest of the crystal, that shows deeper coloring. Some of the samples of these properties have either a brown or blueish coloring, but other colors are not out of the question. It shows
pleochroic attributes, meaning depending on which axis the mineral is seen on, it appears as if it is changing colors. On the α axis it is seen in a pale brown, almost pinkish color, but on the β and γ ones, it appears to be colourless. ==References==