This dissertation provides a glimpse into the complexities of solid-state actinide materials by using microscopic and spectroscopic techniques to probe chemical and physical properties, such as surface roughness, morphology, and susceptibility to aging and alteration. Throughout the nuclear fuel cycle, variations in production, processing, and machining provide ample opportunity for material to undergo changes to its macroscopic appearance and microstructure. Understanding how and why these changes occur over time is relevant to the nuclear nonproliferation, safeguards, and forensics communities and could lead to the discovery of new and improved forensic "fingerprints." The work presented herein studies solid-state actinide materials relevant to the nuclear fuel cycle, primarily actinide oxides in either powder or pellet form, using electron microscopy, digital microscopy, optical profilometry, vibrational spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction techniques to identify trends and potential signatures.