Volcanism on earth is always associated with plate tectonic activity.

Volcanism is associated with two of the plate boundary types: divergent and convergent margins. ... Volcanism can also occur at intraplate volcanoes. These volcanoes are believed to have sources deeper down in the Earth's mantle that remain in a relatively fixed location relative to the always migrating plate boundaries.

luster is not a good characteristic to use by itself because luster is the property of minerals that indicates how much the surface of a mineral reflects light. the luster of a mineral is affected by the brilliance of the light used to observe the mineral surface.