Note: In a thin section it often exhibits a fluidal structure, marked by the arrangement of microlites in the lines of the flow of the molten mass.
OBSIDIONAL Ob*sid"i*o*nal, a. Etym: [L. obsidionalis, from obsidio a siege, obsidere to besiege: cf.F. obsidional. See Obsess.]
Defn: Of or pertaining to a siege. Obsidional crown (Rom.Antiq.), a crown bestowed upon a general who raised the siege of a beleaguered place, or upon one who held out against a siege.
OBSIGILLATION
Ob*sig`il*la"tion, n. Etym: [L. ob (see Ob-) + sigillum a seal.]
Defn: A sealing up. [Obs.] Maunder.
OBSIGN
Ob*sign", v. t. Etym: [See Obsignate.]
Defn: To seal; to confirm, as by a seal or stamp. [Obs.] Bradford.
OBSIGNATE
Ob*sig"nate, v. t. Etym: [L. obsignated, p.p. of obsignare to seal.
See Ob-, and Sign.]
Defn: To seal; to ratify. [Obs.] Barrow.
OBSIGNATION
Ob`sig*na"tion, n. Etym: [L. obsignatio.]