In case you wanted to know about it.
Featured in the fanfic Monster Hunter reBirth, Crystalwood is a valuable new type of ore found in the wreckage of Guildcorp city, near Biome-H. Before the Asteroid struck the city and transformed half the world into a mideval state, high-rise highway supports were made out of a special cement fused with diamonds. The radiation from the asteroid gave the diamonds life, transforming the pillars into trees. Crystalwood has the same rarity of rust shards.
Crystalwood's most unique feature is its absorption abilities. When used against a certain monster, Crystalwood will transform into unique equipment based on the monster's abilities. Eg. In chapter 11 of reBirth, Tamara's Crystalwood LBG transforms into the Mossberg LBG, after taking a hit from the Mekaroa.