wiki has it:
Referenced throughout the Talmud and the Midrashim, the Shamir was reputed to have existed in the time of Moses. Moses reputedly used the Shamir to engrave the Hoshen (Priestly breastplate) stones that were inserted into the breastplate.[2] King Solomon, aware of the existence of the Shamir, but unaware of its location, commissioned a search that turned up a “grain of Shamir the size of a barley-corn”.
Solomon’s artisans reputedly used the Shamir in the construction of Solomon’s Temple. The material to be worked, whether stone, wood or metal, was affected by being “shown to the Shamir.” Following this line of logic (anything that can be ‘shown’ something must have eyes to see), early Rabbinical scholars described the Shamir almost as a living being. Other early sources, however, describe it as a green stone. For storage, the Shamir was meant to have been always wrapped in wool and stored in a container made of lead; any other vessel would burst and disintegrate under the Shamir’s gaze. The Shamir was said to have been either lost or had lost its potency (along with the “dripping of the honeycomb”) by the time of the destruction of the First Temple[3] at the hands of Nebuchadnezzar in 586 B.C.
http://en.wikipedia.org/wiki/Solomon%27s_shamir
That description is puzzling at best. :’) I’m more inclined to believe that the Baalbek megalithic stones were cut and set in place in pre-Conquest (and even prehistoric) times, then repurposed by the Danites, but I’m flexible in this regard. :’)