I love, love, love Selenite hearts. Geologically the crystal is called gypsum variety satin spar. Gorgeous to hold and stroke. Unfortunately it is too impractical for young children to play with.
The optics play beautifully with the light for these selenite hearts. The “faults” are actually little selenite crystals in the satin spar. It is really magical to look at when the light hits the crystals. Its truly amazing that these can even be polished to such a lovely shine so put a light under it and watch it glow.
Dimensions are approximate but the photo is a good sample of what we have as they all look very similar. Do NOT leave these soaking in water as the structure absorbs it and goes odd.