Petrified wood? Tusk?

[gtdkate]

Hi, there! I’m so impressed by this forum. You all have given such good directions for how to post. Fingers crossed that I dotted all of my i’s and crossed all of my t’s. 
 

I purchased this at a local auction as part of a larger lot labeled “Rocks”. Auction was in Eastern Nebraska near Freemont. 
 

I would be so grateful for any insights as to what this is. 
 

— gtdkate 

[Fossildude19]

Not seeing any wood grain or growth rings. 

I think this is a pet wood mimic, piece of chert/agate/chalcedony.

[Rockwood]

I wouldn't wager much against the opinion, but it could still be wrong. Some wood lacks macroscopic preservation of details. Absent context to relate this to better studied specimens it will be tough to identify without lab. equipment I'm afraid however.

[Harry Pristis]

 It's common to identify petrified wood by evidence of wood grain or growth rings.  This is PERMINERALIZED wood which has some residual organic remains.

 

Contrast that wood with pet. wood that is REPLACED by some mineral or other.  Silica is common, but is not the only replacement mineral.  Totally replaced wood is massive, that is, it has no residual wood grain or growth rings.  However, replaced wood may preserve the external form of the wood, modeled in the replacement mineral.  There are many examples, but here are some replaced by fluorapatite I've collected: