What is a lamprophyre in geology ?
Lamprophyre : definition
A lamprophyre is a dark lode magmatic rock, characterized by the abundance of ferromagnesian minerals : biotite (or phlogopite), and / or brown amphibole (up to 20% of the rock). The rest of the rock is composed of feldspar, clinopyroxene, sometimes olivine (altered), analcime, or even quartz or calcite. These original rocks have a very variable chemistry, ranging from composition of granites to those of basalts, sometimes ultrabasite. Minette and kersantite are two varieties.