Question

Which one of the following minerals does NOT show changes in optical properties upon exposure to UV light?

• A. Apatite
• B. Calcite
• C. Fluorite
• D. Scheelite

Hint:

Fluorite, calcite, and scheelite are classic fluorescent minerals, whereas apatite usually shows weak or no fluorescence.

Answer 1

The Correct Option is A

Step 1: What UV light does to some minerals.
When ultraviolet light hits certain minerals, they glow with a new colour. This glow is called fluorescence and it is a clear change in optical behaviour.

Step 2: We need the odd one out.
The question asks for the mineral that stays the same under UV light. So we look for the one that does not glow.

Step 3: Recall the strong glowers.
Fluorite is the classic mineral that glows under UV, in fact the word fluorescence comes from it. Scheelite gives a bright blue glow and is used to spot ore. Calcite often glows red or other colours from tiny impurities.

Step 4: Look at apatite.
Apatite does not give any steady or strong glow under UV. Its look stays nearly the same, so its optical properties do not change.

Step 5: Final pick.
So the mineral with no change is apatite.
\[ \boxed{\text{Apatite}} \]