Researchers have created a new material named davyne, which changes color in the near-infrared region of the light spectrum — a range that is invisible to the human eye. This material was discovered during studies of hackmanite, a natural mineral that can also be made in a lab. Hackmanite is known for its ability to change color when exposed to ultraviolet light, shifting from white to pink or violet. However, the color returns to normal when exposed to visible light or heat. The discovery of davyne, which has different properties, is described in the journal Angewandte Chemie International Edition. The development of davyne began as part of a student’s thesis project, where the team experimented with replacing sodium in hackmanite with calcium. This change altered the color response, causing the material to turn yellow instead of pink or violet. Some samples of this modified hackmanite showed color changes in the near-infrared range — a region of the electromagnetic spectrum that humans cannot see. This property makes it potentially useful for applications that require covert, invisible markings. Davyne is a member of the cancrinite mineral family and was created as a byproduct of synthesizing calcium hackmanite. While calcium hackmanite and davyne have the same chemical formula, their atomic structures differ. Initially, producing pure davyne was difficult because the chemical process naturally favored the formation of calcium hackmanite. The research team used machine learning techniques to refine the synthesis process and successfully produced davyne in greater purity. The color-changing mechanism in davyne is similar to that of hackmanite, involving the movement of an electron from one ion to a chlorine vacancy in the material’s structure. However, unlike hackmanite, which has small cavities, davyne has long, open tunnels in its structure. This structural difference allows davyne to change color in the near-infrared range, which can only be detected using a spectrometer or an infrared-sensitive camera. Davyne is unique because it is the only known material that changes color in a way that is invisible to the human eye. This makes it a promising candidate for use in anti-counterfeiting measures or security markings. Tests have shown that its color change can be clearly detected under infrared light when the camera's sensitivity is adjusted. Additionally, the material’s near-infrared activity can be turned on and off, allowing the marking to be activated for inspection and then hidden again, offering a high level of security and flexibility.