The phrase "a very tiny portion" is correct and usable in written English.
It can be used to describe a small amount of something, emphasizing its small size.
Example: "In the experiment, we only used a very tiny portion of the sample to ensure accurate results."
Alternatives: "a minuscule amount" or "a small fraction".
In a way, I guess, I would say, a freeze that starts next year on a very tiny portion of the budget, which President Obama announced the other night, simply isn't a serious effort.
Keen: I think you're referring to a very tiny portion of the Internet users.
Each micrograph usually represents a very tiny portion of a section, which is in turn derived from blocks, fragments or slices of the organ or cell pellets.
For instance, these companies often offer only to genotype the uniparental markers (the mitochondrial DNA [mtDNA] and/or the Y-chromosome [ 23]); however, these markers behave as single locus and therefore can only reflect a very tiny portion of the genomic individual ancestry [ 24, 25].
Given that the tumor often represents a very tiny portion of the body mass, microvesicles/exosomes secreted from the tumor cells are less likely to be sufficient enough to change the miRNA profile in a large volume of blood (5 L in a 72-kg person).
But Davidar wishes it to be known that sex scenes will constitute "a very, very tiny portion" of the finished book.
My estimates of the energy value of home-cooked foods were at first a bit off, so I ate a lot of very tiny portions.
Television stunt coordinators receive a minute portion of a very tiny residual pool compared to the maximum residuals ($3450 per episode) of the actors they supervise.
As shown in Fig. 1c, if a parent droplet experiences electrowetting forces by two electrodes arranged diagonally, the droplet will conform to the electrodes shape to have two diamond portions connected with a very tiny liquid bridge.
They were essentially an H.M.O., though a very tiny one.
