70s (or earlier) children's sci-fi novel with tiny intelligent gemstones falling from the sky, a kid forms a mental connection with them

Question

I'm trying to remember the name of a (children's?) sci-fi novel I read as a child in the mid-80s, but it might have been written in the 1970s or earlier.

It was about tiny coloured gemstones that fell from the sky all over a city. Two/three young friends collected some up, then discovered the gemstones were intelligent. The gemstones would connect together to form different shapes and spell out words. One of the friends, I think, formed some sort of mental connection with the stones and could manipulate them.

Have searched for it online but can't find anything that fits my recollection.

Answer 1

I'm pretty sure that's Trillions by Nicholas Fisk, which is indeed from the 1970s.

Trillions were hard, bright, tiny things which suddenly arrived, millions and millions and millions of them, one windy day in a village called Harbourtown.

No one could explain them, much less why they had suddenly arrived. Were they a blessing, as their beauty suggested, or a deadly, inexplicable threat?