Zeolite is a group name for a large number of microporous framework alumosilicates which are built of corner-linked tetrahedra and contain exchangeable cations.  This porous structure allows a wide variety of loosely held positive cations (Na+, K+, Ca2+, Mg2+) to be readily exchanged for others in a contact solution - hence one of the many uses of zeolites is in ion-exchange applicaitons (micro-sieving).  

The term zeolite is attributed to Swedish mineralogist Axel Cronsetedt, who in 1756 observed that rapidly heated material (believed to be stilbite) produced large amounts of steam from water that had been adsorbed by the material [from the Greek - zeo, to boil, and lthos, stone].  Over 232 unique zeolite frameworks have been identified with over 45 occuring naturally.  Zeolites are produced industrially on a large scale for such applications as commercial adsorbents and catalysts, water purificatiion, separation of gases and molecules, on-board oxygen generating systems, solar thermal collectors, and non-clumping cat litter. 

The largest single use is the global laundry detergent market.  Natural zeolites form where volcanic rocks and ash layers react with alkaline groundwater or in shallow marine basins (over periods of thousands to millions of years). 
Thomsonite has been collected as a gemstone from a series of basalt lava flows along Lake Superior in Minnesota.

Some of the natural Zeolites available at Taos Rockers include:

Analcime       Na(AlSi2O6) · H2O

Chabazite      CaAl2Si4O12 · 6H2O

Heulandite    CaAl2Si7O18 · 6H2O

Laumontite    CaAl2Si4O12 · 4H2O

Mordenite      (Na2,Ca,K2)Al2Si10O24 · 7H2O

Natrolite         Na2Al2Si3O10 · 2H2O

Mesolite         Na2Ca2Si9Al6O30 · 8H2O

Scolecite        CaAl2Si3O10 · 3H2O

Pollucite        (Cs,Na)2(Al2Si4O12) · 2H2O

Stellerite        Ca4(Si28Al8)O72 · 28H2O

Stilbite            CaAl2Si7O18 · 7H2O

Thomsonite   (Ca,Na)6Al8(Al,Si)2Si10O40· 12H2O

Along with other minerals often found associated with zeolites:
Apophyllite    NaCa4(Si8O20)F · 8H2O

Cavansite      Ca(VO)Si4010· 4H2O

Prehnite         Ca2Al2Si3O10(OH)2