This lesson explores the zinc–copper alloy used in modern coinage, focusing on the U.S. one-cent coin (penny) produced after 1982. Students will examine how the transition from solid copper to zinc-based alloy reduced production costs, and how XRF spectroscopy reveals the layered composition of plated metals. The lesson introduces the concept of plating and its impact on XRF results.
Objectives
-
Understand the composition and properties of zinc–copper alloys used in coinage.
-
Recognize the difference between true alloys and plated metals.
Materials
-
U.S. one-cent coins (pre- and post-1982)
-
Sandpaper or abrasive tool
Lesson Plan
-
Discuss the historical change in the composition of the U.S. penny and reasons for adopting a zinc-based alloy.
-
Perform XRF analysis of the coin surface and discuss spectral peaks for copper and zinc.
-
Lightly abrade the coin surface and reanalyze to reveal the underlying zinc-rich alloy.
To reinforce the concepts discussed here, we also provide a video lesson that visually walks through the key points of this topic. Watching the video alongside the text can help you better understand and apply these ideas in practice.
The course XRF Spectroscopy for Art Examination introduces conservators, art historians, and scientists with interest in Art to the principles and practical applications of X-ray fluorescence (XRF) spectroscopy in the examination of artworks. The course starts with basic principles of XRF and gradually explores its role in identifying materials and methods used in the creation and conservation of art.
Course Objectives
- Understand the fundamentals of XRF spectroscopy and how it applies to the analysis of art.
- Learn the key features and limitations of XRF for examining art and archaeology.
- Gain skills in interpreting XRF spectra to identify specific elements in paint layers, inks and metals.
