Definitions for "Authigenic"
Formed or generated in place. Said of rocks or minerals formed at the spot where they are now found.
minerals that form in situ in sediments after deposition.
Formed or generated in place; specif. said of rock constituents and minerals that have not been transported or that crystallized locally at the spot where they are now found, and of minerals that came into existence at the same time as, or subsequently to, the formation of the rock of which they constitute a part. The term, as used, often refers to a mineral (such as quartz or feldspar) formed after deposition of the original sediment.
Geologist's word applied to crystals. Ask a geologist what it means for certain, but something like "all pointing the same way".
A term implying a development in place during or after deposition.