Gandalf's Symbol--an Elvish letter???

[piosenniel]

Child -

The symbol is a cirth:

from Encyc. of Arda

Dates: Predate the beginning of the First Age
Origins: First devised by Rúmil of Tirion1
Meaning: From Old Norse rún, meaning a magical symbol2
Other Names: Cirth


A system of writing based on angular shapes that could easily be carved into wood or stone. Originated by Rúmil and greatly developed by Daeron of Doriath to represent Sindarin words, runes came to be used widely by races other than the Elves, and especially by the Dwarves.

You can also read about them in ROTK, Appendix E

The particular one you mentioned was the rune representing 'G'. I don't know why it has the 4 dots arranged around it - other than for effect, or possible that it is meant to stand alone as his initial.