Hi there, I have some extra pieces of Yixing clay from a teapot that broke. If you want, I'll mail you some in an envelope for the cost of shipping. If you want to test it out, all you need to do is brew some tea into a pitcher, pour into 2 identical cups and drop a shard of clay into one of the cups. Feel free to remove the clay shard after a minute, have someone else switch around the cups (or not) and taste both cups.

For what it's worth, I have verified with TDS meter readings and refractometer readings that unglazed clay (not just Yixing) does in fact affect the tea in various ways, these changes being in isolation of thermal or other properties in relation to brewing the tea.

Keep in mind that the water you brew with affects how much the clay will change the tea. Some waters are highly clay-sensitive, meaning when you brew a tea in a teapot with such a water, the tea comes out tasting very bland and muted even though the same water/tea is fine in porcelain. I struggled with this for the longest time until I realized that reducing sulfate content of the water was a huge help in reducing clay-sensitivity of water. Anyway, I digress.

This is also worth reading. Most of the elements mentioned have distinct effects on the water, which extracts from the tea when brewing (I don't mean to oversimplify, clay has multiple mechanisms for interacting with tea and water. One other being porosity, which affects which and how many molecules are absorbed from the tea into the clay so that you won't taste those molecules when you taste the tea). You don't even need clay to experience relevant changes in the tea, just add some mineral (e.g. sodium bicarbonate which is baking soda, or magnesium sulfate heptahydrate which is epsom salt) to your kettle, boil the water and brew. You can also add colloidal silica (Eidon brand recommended) to mimic the effect of silicon dioxide dissolution from Yixing clay. You'll notice tremendous differences, especially if you brew raw puer.

Edited for clarity and to add further info. Let me know if you have any questions. Cheers