Dave GriffithsA new one for me - specular hematite (aka specularite), bright silver hexagonal plates and metallic masses in a dark matrix. It got an ultrasonic clean, but otherwise as found, near to one of the concrete ore washing buddles at Bassett and Grylls mine, Wendron, Cornwall.
There is a lot of really shiny mica and coal dust on this site, but even with a crust of clay over most of it, it it was obvious that this was much brighter, sparkly mineral when I picked it up.
According to "The geology of Poldark Mine and it's surrounding area" by N. G. LeBoutillier, this mineral is a high temperature one that occurs in the "roots of the lode", indicating that there is not much tin left below - most of it has eroded away from kilometres of rock above the current surface level a long time ago. This is the reason so much of it was present in the soil and stream sediment in the area.
mindat.org minID: V04-YHW
Field of View: 2.5 - 10mm
#Cornwall #MicroMinerals #Fossicking #CornishMinerals #MineralSpecimens #Crystals #FossickingCornwall #Mineralogy #MineralCollecting #GeologyRocks
ERAT
Doug Merson