Draba norvegica; Rock Whitlowgrass resembles the hoary whitlowgrass (D. incana) but it has only one or two leaves on the flowering stems. As such it also resembles the snow whitlowgrass (D. nivalis) which has no leaves on the flowering stems and the rosette leaves are densely grey-haired. The rock whitlowgras has brighter green foliage. The leaves and stems are, however also covered with short hairs. If you have a magnifying glass you can see that the hairs are star-shaped (called "stellate") or forked. This characteristic feature is also found in the snow whtlowgrass (D. nivalis). See the photo blow-up of stellate hairs. The rock whitlowgrass is common and can be found in all regions of Iceland. The color of the flowers (petals) are white. In the first photo the plant shows violet sepals. They can be green too.
It is a member of the cabbage (= mustard) family) (Brassicaceae formerly known as Cruciferae). The Icelandic name of this species is Hagarvorblóm.