Per Wikipedia's article on petrified wood, it's usually quartz, which is harmless. Various other elements can be present:
Elements such as manganese, iron and copper in the water/mud during the petrification process give petrified wood a variety of color ranges. Pure quartz crystals are colorless, but when contaminants are added to the process the crystals take on a yellow, red, or other tint.
Following is a list of contaminating elements and related color hues:
carbon - black
cobalt - green/blue
chromium - green/blue
copper - green/blue
iron oxides - red, brown, and yellow
manganese - pink/orange
manganese oxides - black/yellow
In rocks, copper will usually show up as green. The only part that bugs me is that your wood is soft enough for it to flake off. That means whatever your rock is now, will end up in your tank. If it is not inert, you are going to have it leach quicker than if it were harder.
regardless of it breakingdown...is it aquarium safe though? i will post all the the other rocks i got for you guys to see. some of them kinda have traces of these glittery stuff...but the rock above has it the most and kinda looks diffrent from the rest.
ok after taking a bit to review you photos i belive the rocks in your photos are a mixture of Shists, petrified wood and sand stones. sand stones and pertirfied fall in to that catigory of being safe 99.9% of the time only on the rare ocasion do they have enough impurities in the way of metals to be toxic.
as for shists they are a whole nuther story. they are composed of metamorphosed clays and muds associated with the creation of shales and slates. these areas do not become slated because they are under extreme presure and undrgoing fluid movement (but are not liqid aka magma) giving them there distinc look if flowing layers. most of the time these rocks are as stated above clays which will include any minerals that were present in the clay such as hornblends, chlorite and qrtz. on ocasaion thse rocks will include garnets and other suck minerals but thse are from the host weathered rock that created the clay.
this being said your shist should be safe from what i can see i see no large mineral inclusions and the green color is from weathering and is most like leaching of differnet minerals is this is a concern i would place the offending rocks in a seporate contained with ghost shrimp and see what happens.
whew! thank goodness now i have peace of mind. i was planning to get some more from the same source but was put into hold when the sparkly stuff came off. thank you so much metageo.. and thanks to everyone for their input