Crystals As Part of Tarot Spread?

Hey guys, as a Witch and a Folklorist I am well acquainted with the occult properties of crystals (ugh....for the most part!). However, I have observed many Tarotists employing one or several other crystals during their readings or seemingly as an integral part of their spread (like a quasi-mandala or crystal grid). I am curious as to why as these are not mere quartz crystals, but widely varied (though moldavite seems to be very popular with Tarot Readers, for some reason). Neither have I read books by Tarot Authors that have explored layouts with crystals. This is something that I am curious about...

I use certain crystals with some of my favourite decks. The crystal sits in the pouch with the deck and when I read the crystal is on the reading cloth as an integral part of the spread. The crystals vary because all of my favourite decks have different favorites in crystals ( ).
Undersea Tarot and T. of Mermaids both have their own aquamarines. My Vampyres naturally like a bloodstone, etc. Crystal Visions has a quartz crystal but just because it came with the deck.

I have heard that both black toumaline (for grounding and for repelling negativity) and amethyst (for spiritual vision and clarity) are among some of the most popular.

There are several crystal resources (books, websites) that will tell you about the uses of crystals - as to how they pertain to tarot though, not as sure! You can always ask here which crystals people use when they read, and why...

Meanwhile, here is an excellent guide made up of snippets from every crystal book out there!

http://www.crystalvaults.com/guides-crystals/

It is the most comprehensive list of crystal use and meaning I have found on the web

I like to keep pietersite with my cards, and usually wear one in a pouch for readings!

Quartz would be useful for magnifying the energies of a reading, but lots of different stoned could be useful, especially depending on the reader's needs. Maybe you would want something to help with communication, or stay relaxed, or for grounding... Or maybe to open up to inspiration, which is my experience with pietersite.

I've also used stones with cards to weigh them down when reading outside... I sometimes chose stones that seemed fitting for each card, but mostly it was serving a practical function, rather than as part of a reading.