Jeffrey Anderson writes on his website dwarves earth-treasures about this material :

“... The Iron Lace agate, as named by the Ispheming Club, has been obtained out of a single vein of agate by an interested iron miner from the open-pit Republic Iron Mine of Michigan during its active mining periods (1970s). It is not known if any more agates are still available from that mine, but it is possible to find some more if one is willing to overturn tons of rocks at the mine dumps. Covering the botryial masses of hematite, the agates were found as the forms of thin seams within the metamorphic iron formations. The most common colors are white and yellow and the rare bright red color would be most desired color of all. Until someone comes foward with diferent tyep of agate from different location, this type of agate is one of very few agate types found in the metamorphic rocks. ...”