The Stan rune, the 32nd of the Northumbrian Futhorc is one of the graal runes:
"It seems that the 'magical formula' calc-stan-gar actually represents an esoteric understanding of the Grail mythos which was well-developed in the Germanic world. Although Wolfram refers to southern sources from Moorish Spain, no hard evidence for this understanding has actually come from there. So we are left with Wolfram's lengthy discourses in Parzival as well as other discussions in medieval German works, e.g., the Wartburgkrieg of Heinrich von Ofterdingen, in which the Grail is also identified with a stone that fell from Lucifer's crown, and the Old English runic tradition, as sources for the chalice-stone-spear complex." (ALU. An Advanced Guide to Operative Runology, 2012, Edred Thorsson.)
He places the origin of the calc-stan-gar (horn/chalice-stone-spear) complex among the Alans, a North Iranian people who were stationed in Northumbria in Roman times. Herodotus explains that the Sythians who the Alans were closely related to had an origin myth that concerned three golden objects that fell from the sky, a plow and yoke, a battle-ax and a cup. These three objects represent the three Dumezelian functions of fertility, war and priestcraft, the three Aryan castes. Dr Flowers (Edred Thorsson) comments that the stone (Stan) represents earth (fertility), the spear (Gar) represents war and the chalice (Calc) priestcraft.
In Irish mythology in the Second Battle of Mag Tured the Tuatha De Danann (the Aesir of Germanic mythology) bring with them to Ireland the four sacred objects of the Stone of Fal-symbolised by the Stan rune, the Spear of Lug (the Celtic equivalent to Woden)-symbolised by the Gar rune, the sword of Nuada (the Celtic equivalent to Tiw)-symbolised by the Tiwaz rune and the Dagda's cauldron-symbolised by the Calc rune.
According to Nigel Pennick in his Wyrdstaves of the North. Runic Lore and Legend of Old Northumbria (2010):
"Stan represents the Bones of the Earth, the ground beneath our feet. It can signify a blockage, such as a rock lying across a path, or a stone at the entrance to a cave. Additionally, Stan represents a megalith standing at a place of power in the landscape, a wyrdstone bearing natural runes which we can read, or a stone or playing piece in a board game."
I believe that Mr Pennick is correct. The more that I meditate upon Stan the more I visualise a megalith and in particular I visualise the White Horse Stone or Inga Stone which is near Aylesford in Kent for it has the general shape of Stan, very much like an ancient altar stone. This stone is said to be a memorial to the fallen chieftain Horsa.
Another rune which resembles in shape a megalith, indeed a dolmen is the Uruz/Ur rune, the second rune. Not only does this rune visually remind us of a dolmen but its very meaning-strength is surely indicative of these heavy stones. A secondary meaning is to be found in the name of the rune itself-Ur, the Germanic for ancient, primaeval. Megaliths portray both these qualities-strength and antiquity.