Sonora Dendritic is a new find from Sonora, Mexico. The Gem Shop offers an interesting story about how a goat helped to find it. The story along with photos of the gorgeous, virtually inaccessible location of the site are here. Gene calls the stone an "altered dolomite" but sometimes it is referred to as a rhyolite.
The crystallization of manganese oxides in stone can form fractal patterns called dendrites because they mimic branching life forms. So the "tree" in this pretty stone is not a fossil but a mineral formation. There are lots of different manganese oxides which form dendritic patterns, it is interesting that the unusual color of the dendrites in Sonora Dendritic is virtually identical to that in another unusual stone, Apache Sage jasper from New Mexico (an example of Apache Sage from my website can be found here).
This lovely material hasn't made its way into the metaphysical texts yet, but Melody speaks of Dolomite as assisting one to recognize that everything happens for a reason, thus can be helpful in relieving sorrow. Ahsian mentions it lends a calming energy to the emotional body. Please note that when I mention something from these authors (which you can find linked below) I am choosing one characteristic from sometimes pages of fascinating discussion. If you have an interest, please realize there is vastly more to learn from these texts and others. And/or from the stone itself! Why not order this lovely landscape and see what it whispers to you?