Doros is a layered gabbroic intrusion the only alkaline rocks being late aegirine bostonite dykes. The intrusion is 7x3.5 km and pear-shaped. The western intrusive margin is against Damara metasediments and Salem granite, but elsewhere is with Karoo sediments; the contacts dip inwards at 39-51°. Seven layers were mapped by Hodgson and Botha (1974) including a lower chill zone, while the third layer from the bottom is intrusive and partially transgressive. All the contacts are sharp. The layers consist essentially of plagioclase, pyroxene, olivine and magnetite differing in their proportions and compositions. Olivine is exceptionally abundant in the lower layers (>40%) and minor towards the top, while plagioclase and pyroxene increase markedly upwards. The bostonite dykes, which are up to 500 m long and 2 m wide, consist of about 85% orthoclase with the rest interstitial aegirine. Rock analyses for the layered series are given by Hodgson and Botha (1974).