There is a picture at the bottom of this page. It was taken on a newly staked mineral claim in the Rice Lake Greenstone Belt of Manitoba. It's a picture on a vein exposed on the surface in an outcrop on the shoreline of a lake. In that picture I am leaning on a section of that vein. It is composed of Quartz and a few other things. (assays will tell)
We were propecting a section of the property and discovered this. There are not a whole lot of places that you can see a vein this size that is exposed enough to get a real idea of it's size.
That feature was formed as the result of fluids flowing into a good sized crack in the host rock and it seems that it altered the rock into which it formed. There is a shear zone to the left.