Here's a link to Vacor's present webite: http://www.vacor.com.mx.
It's a neat site. Check it out. They've got interesting pix of applications for marbles in the "industrial" section, as well as a slick slideshow of marble styles in the "juguete" section.
The text quoted below is from their history page. If I'm reading it correctly, it says they started out making clays in 1930, and in 1934 made clearies, and then started cat's eye production in 1944.