This is a beautiful cluster of "tangerine" quartz crystals, from Madagascar. The longest crystal is 5.3" long. The base of this cluster has been cut flat, allowing for aesthetic presentation of the crystals without the need for a display stand.
The underside of this specimen is unique in that much of the base is made up of double terminated quartz crystals.
These clusters are natural and not heat treated or coated. The orange color is due to a combination of Iron, Hematite and Manganese coating the surface of the crystals but may also be present as inclusions within the crystals themselves. A likely cause is a high iron content in the soil where these crystals are found.
Lower quality material often with lots of surface damage is present on the market from Brazil, but this is some of the first high quality, natural specimens I've seen from Madagascar.