Hrungnir was one of the giants from Jotunheim. On one visit to Aasgard, Hrungnir drank all the ale from Thor’s cups. While he was drunk he boasted that he was going to drink all the ale from the Aasas. Thor took insult and slayed him in a duel. Hrungnir had a heart of stone, sharp and three-sided, and even his head was of stone. But Thor defeated him with his hammer.
The special shape of Hrungnir’s heart is also known as a Valknut – a knot of three interlocking triangles. In Skáldamál (part of the Prose Edda from the 13th century) it says “Hrungnir had a heart that was famous. It was made of hard stone with three sharp-pointed corners just like the carved symbol hrungnishjarta [Hrungnir’s heart]”, and the symbol can be found in a number of different stone carvings, including one at Stora Hammars on Gotland, Sweden.
Double-knitting is a form of two colour knitting that produces a completely reversible fabric. Each side looks like stockinette knitting – but the colours are reversed between the two sides. There are no visible floats, and thus no “wrong side” of the scarf.
The pattern is available as a PDF download, and includes detailed instructions on two different methods of double-knitting.
For my scarf, I used Arial from Twisted Fiber Art. One skein is in the colourway shadow (blue), and the other is a Twisted Evolution in Firefly – long colour-runs going from bright yellow to gray.