Zeolite Mineral Group
Rock&Gem Magazine|April 2020
MOLECULAR STRUCTURE AND MATCHING PHYSICAL ATTRIBUTES DEFINE AND UNIFY
BOB JONES

Scientists have identified about 5,000 different mineral species. With so many minerals, it’s not surprising for several to have closely matching physical and chemical similarities. Scientists have established a grouping system for species with closely matching properties to provide for ease of study. Some groups only have three species, the minimum required. Other groups like the mica and autunite groups have more than 40 members.

The zeolite group is unusual, as it is considered to be two separate groups. Zeolites in the main group have all the required properties to be in that group. Other zeolites have the same properties, save for one or two that are different enough to be treated separately. Combined, the two groups include more than 75 members. Zeolites form when hot volcanic rocks react with groundwaters. The more prolific sources of zeolite minerals are in areas of vast volcanism. They also occur in ore veins and sedimentary rocks.

There is also some confusion about zeolite minerals. Collectors often assume any mineral found in a zeolite environment is a zeolite, but it’s not so. Such beauties as cavansite and apophyllite are two species mistakenly thought to be zeolites. Because of this, the second group of non-zeolites is often treated with the zeolites. To help distinguish between them, we’ll offer two companion articles, “Zeolites” and “Non-Zeolite” in future issues of Rock & Gem.

In a brief article like this, it would be a physical impossibility to describe every one of the 75 or so known zeolites. Some are rare and seldom seen. Others are known only to the micro-mounter using special equipment. In this article, we’ll treat zeolites most often seen at shows and are enjoyed by the average collector.

DEFINING ASPECTS OF ZEOLITES

The first obvious question is, “What’s a zeolite?” The name comes from zein which is Greek for “to boil,” because they often do just that when heated in a closed container. Several other criteria define a zeolite, the most important being its molecular structure. Each has to have a three-dimensional network that presents either in sheets, cage-like, or chain-like. In each case, the molecular structure must be an open network. Chemically a zeolite must contain AlO4 and SiO4 in tetrahedron form, and these must share their oxygen atoms, which makes the three-dimensional cage-like structure possible. Water must also be present, as well as ions of alkali or alkali earth metals that have replaced to some degree the aluminum or silicon oxides. It is this structure that gives zeolite its filtering action to capture impurities in the water as it passes through.

This is a simplified explanation of why a zeolite works, but it also helps us understand why zeolites can act as filters and be sieve-like.

This open structure and the presence of chemically active alkali or alkaline earth elements make the zeolite become negatively charged as water runs through it, and this attracts the water’s impurities turning hard water into more useful soft water.

When a zeolite is heated it dehydrates, water is lost as it appears to boil hence the name. This loss does not change the molecular structure of the mineral’s open network.

PHYSICAL ATTRIBUTES AND LOCALITY

Continue reading your story on the app

Continue reading your story in the magazine

RELATED STORIES

SUJATA MASSEY

Sometimes, an idea needs time to incubate until it’s ready to grow. That was the case with Sujata Massey’s series about Perveen Mistry, a woman attorney practicing in India during the 1920s.

10+ mins read
Mystery Scene
Summer #168 2021

SHOWSTOPPING

THIRTEEN FASCINATING 4X4S from the2020 Fall 4-Wheel Jamboree Nationals

9 mins read
Four Wheeler
July 2021

4X4 PARTY!

Recap of the 39th Annual O’Reilly Auto Parts Fall 4-Wheel Jamboree Nationals

5 mins read
Four Wheeler
July 2021

Klara Landrat & Her Journey with Endometriosis

Klara Landrat is an American-Israeli actress of Polish origin, producer, a writer known for her talent worldwide. She is starring in the Irish TV series – “Gods & Fighting Men” due for release in 2021.

6 mins read
Women Fitness
March 2021

HER MAJESTY PEDDLING HOMEMADE HOOCH!

QUEEN ELIZABETH looks like a dowdy, straitlaced granny, but she’s turned into a heck of a bartender — serving up her own brands of homemade hooch!

1 min read
Globe
May 24, 2021

The Winter of Discontent

Even though america is preparing for a summer reopening, the Coronavirus will still be around to dog us when the temperatures fall.

10+ mins read
Newsweek
May 21 - 28, 2021 (Double Issue)

India thought it had the virus beat. The virus had other ideas

Governments around the world keep repeating the same mistakes. In a country of 1.4 billion, the consequences are on a whole new scale

10+ mins read
Bloomberg Businessweek
May 17, 2021

Reincarnation And Realpolitik

China, India, and the U.S. are vying to influence the selection of the next Dalai Lama

5 mins read
Bloomberg Businessweek
April 19, 2021

An Exclusive Interview With Nandakumar Narasimhan

The Little Red Train

10+ mins read
Lens Magazine
March 2021

A Room for Dad

Before Mom passed, I made a promise to her

8 mins read
Guideposts
April 2021