[1] The Kiruna Porphyry formed 1,880 to 1,900 million years ago[1][2] during the Paleoproterozoic Era in connection to the Svecofennian orogeny.
[2] While generally well-preserved for its age at some locations such as Malmberget the Kiruna porphyry is more metamorphosed.
[1] In detail, various rock types are distinguished in the Kiruna porphyry such as trachyandesite lava and quartz-bearing porphyry of rhyolitic composition.
[1] Part of the quartz-bearing porphyry is thought to be ignimbrite.
[1] The Haparanda Series of rocks found to east near the Sweden-Finland border are thought to have the same origin as the Kiruna porphyry.