Quartz

Steven Dutch, Professor Emeritus, Natural and Applied Sciences, Universityof Wisconsin - Green Bay

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Plane-Polarized Light

• Low relief
• Clear
• No cleavage
• Usually free of inclusions

Crossed Polarizers

• Gray to white interference colors, sometimes to light yellowish white
• Undulose extinction common, often with a fan-like pattern (A)
• Grains with highest interference color sometimes look yellowish-brown near extinction (B)

Quartz, the feldspars, cordierite and nepheline all have low relief and gray to white interference colors. Beginners find them hard to tell apart. View Quartz and its Look-Alikes.

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A view of quartz in crossed polarizers. The undulose extinction and segmentation into domains of slightly different optical orientation are well seen here.

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Created 22 Sept 1997, Last Update