What another word for speck?

Here are some words for speck, depending on the context:

For a tiny particle or spot:

* Dot

* Fleck

* Mote

* Grain

* Particle

* Atom (figuratively)

* Grit (if it's rough or abrasive)

* Scum (if it's on a surface)

For a small amount:

* Trace

* Hint

* Whiff (for a smell)

* Dash (for a liquid)

* Pinch (for a solid)

For a small blemish or imperfection:

* Flaw

* Blemish

* Defect

* Mark

To give you the best word, please tell me:

* What is the speck made of?

* Where is the speck located?

* What is the overall context?