This is an excellent chalcopyrite Crystal isolated on top of a drusy calcite bed. I can scratch it with my nails, so I know it's not quartz even though it looks like it. 
Under the perfect chalcopyrite, sometimes called peacock ore, crystal and the calcite, there is another creamy layer of mineral. I believe it is dolomite as it matches the colour of similar material found in the area.
This Scottish mineral specimen was sitting on a rock pile just off the Southern Uplands Way in Dumfries and Galloway. It is a Dec/January 23/24 crystal.