Hello all, I recently received a very large stone found by my great grandfather. It was found near Carlsbad and it is a bright, almost neon, yellow-green. Most of it is very clear however, there are cloudy spots in it. My father and I have been trying to figure out what it is and after a lot of research we believe it may be sphene. Also, it is a five pound stone and I was wondering what it would be worth if it were sphene.