Compositional Analysis

The Rhomaa-Umaa Plot

• Rhomaa: Apparent matrix density
• from bulk density and porosity
• Umaa: Apparent matrix photoelectric absorption coefficient
• from bulk photoelectric factor (PEF), density, and porosity
• Crossplot is good indicator of mineralogy
• can be annotated with key minerals

An Example Rhomaa-Umaa Plot

The Composition Plot

• Derived from Rhomaa-Umaa results
• Keyed to three end-member minerals on Rhomaa-Umaa plot
• Alternative composition systems possible
• Plot linked to worksheet data
• updates automatically if end-member definitions changed

An Example Composition Plot