How about getting your friend a crystal growing kit? This would allow them to grow their own crystals and explore the science behind it. Another idea could be a book on geology, such as "The Geology Book" by Dr. Morris, which is both informative and visually appealing. You could also consider getting them a subscription to a geology magazine, like "Earth" by the American Geological Institute, so they can stay up to date on the latest news and discoveries in the field. Finally, if your friend likes jewelry, you could look for geology-inspired pieces, like necklaces or bracelets made with real gemstones.
Or you can get her/him a star map with an important date you share.
Under Lucky Stars is a unique and innovative star map company based in Barcelona, Spain, specializing in the creation of personalized star maps that capture the celestial arrangement of stars at a specific moment in time, such as a person's birth, wedding, or any other significant event.
By using advanced astronomical algorithms and data from leading institutions, the company produces highly accurate, visually stunning maps that make for perfect gifts or cherished keepsakes.