What does a black or dark blue color indicate on an X-ray scanner?

On an X-ray scanner, a black or dark blue color typically indicates the presence of inorganic materials, which includes lead or heavy metals. This is because these materials have a different density compared to organic substances and allow more X-ray photons to pass through, resulting in a darker appearance on the scan.

When X-rays penetrate various objects, different materials absorb or transmit the rays to different extents based on their density and atomic composition. Inorganic materials, such as metals, are denser and appear darker on the scan due to their ability to absorb less of the X-ray energy. Heavy metals like lead have higher atomic numbers and are effectively dense, which leads to the dark coloration you would see on the scan.

Understanding these principles is crucial for identifying potential threats or prohibited items in security contexts, as it helps distinguish between materials that could pose a risk (like firearms or other metallic weapons) and those that don't.