Banding that is clearly visible in a thin obsidian flake is often undetectable in a hand sample of glass. Not Applicable . Use when the presence of cortex or patina prevents the determination of this attribute. Little to no light passes through the glass. Light passes through the glass but letters and numbers are obscured and cannot be read.
Light passes through easily and letters or numbers can be easily read.
The degree of light transmittance is most often a direct reflection of the degree of crystallinity of the glass. The luster or quality of light reflected from a clean and patina-free fractured surface of obsidian. Not Applicable . Use when the presence of cortex or patina prevents the determination of this attribute. Having a hard, brilliant luster like that of a diamond.