I recently found this mineral crystallised within quartz at a rock crushing plant. Because of this I have no idea where this rock came from as material is transported to the site from a variety of locations. The mineral has a metallic lustre and is dark red / black. It is difficult to determine the crystals' structure because they are broken but a little is still intact and I guess that it is long and hexagonal. I have determined the hardness to be between 5 and 7. I appreciate that the pictures I have provided aren't great but it was difficult to photograph because of the sample being so small. If you want any pictures retaken I will be happy to do so.
Looks like rutile. Commonly associated with quartz, it's a simple titanium dioxide, though less commonly red in color. Nicely posted question, BTW.
My guess is your rock might contain huebnerite. It is brown-ish red to red in color. It is a vein forming mineral and I've seen examples similar to your specimen in metamorphic rock matrix cut by quartz veins. It has a similar tabular crystal shape.