GATE GG-1 · 2026 · GG
Question 44: Crystallography and mineralogy
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Question 44
GGNAT1 markNeeds review
A mineral under crossed nicols displays second order greenish-yellow (Δₘ = 740 nm) interference colour. On introduction of gypsum plate (Δₐ = 550 nm) along the length of the mineral orientation, first order grey interference colour is displayed. The net retardation is ________ nm (answer in integer).
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2026GG
GATE GG-1 2026 · Paper 1
Geology and Geophysics · Original paper archive
- Section
- Section GG
- Question type
- Numerical answer (NAT)
- Marks
- 1 mark
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