Heulandite vs Stilbite: What’s The Difference?

Stilbite and Heulandite are both the names of two mineral group series. They are pretty abundant across the globe and have a myriad of purposes.

However, to look at Heulandite vs Stilbite, it is essential to define each.

Here is a breakdown of both minerals, from what they’re made of to their differences, similarities, and uses.

What is Stilbite?

Stilbite is the general term for a group of tectosilicate minerals belonging to the zeolite family.

Stilbite was previously classified as a mineral genus, but the International Mineralogical Association reclassified this as a series label in 1997, with the mineral species being declared: stilbite-Ca and stilbite-Na.

Stilbite-Ca is hydrous calcium sodium and aluminum silicate, NaCa4(Si27Al9)O7228, the more common of the two (H2O). When it comes to stilbite-Na, sodium takes precedence over calcium.

Since the species are virtually identical, the series term stilbite is often used in the absence of research.

What is Heulandite?

Heulandite is the term for a group of tectosilicate minerals belonging to the zeolite family. Heulandite was previously classified as a mineral species.

Still, the International Mineralogical Association gave it a series classification in 1997, with the mineral categories Heulandite-Ca, -Na, -K, -Sr, and -Ba(sorted out five years later).

The most popular of all is heulandite-Ca, which is hydrous calcium and aluminum silicate.

Tiny quantities of sodium and potassium replace some of the calcium in most cases. In the heulandite-Sr variety, strontium replaces calcium.

The dominant aspect determines the appropriate species name. Since the species are physically indistinguishable, the series name heulandite is still used in the absence of research.

Heulandite vs Stilbite: Similarities

After being discovered in the late 1700s, both minerals were thought to be the same until the year 1818, when researchers discovered that they were a different species.

  • Both mineral series belong to the zeolite family.
  • The minerals that fall under each series are often difficult to distinguish without in-depth research. This leaves them being referred to in general terms as Stilbite or Heulandite.
  • The two groups are believed to have species containing medicinal or therapeutic benefits.
  • They are both used in the petrochemical industry due to their structure’s exposed channels, which serve as a molecular sieve, allowing them to isolate hydrocarbons during the petroleum refining procedure.
  • Heulandite is found in basaltic volcanic formations, amygdaloidal cavities with stilbite and other zeolites, and gneiss and hydrothermal veins.
  • They are both abundant in New Jersey.

Heulandite vs Stilbite: Differences

  • Heulandite can be light pink, yellow, white, green, or even without a definitive color. On the other hand, Stilbite, which can also be colorless, has a myriad of shades, including pink, green, red, blue, salmon, white, yellow, brown, orange, and black.
  • Heulandite has five species in its series, while Stilbite only has two.
  • Stilbite shapes in a different crystal pattern; otherwise hard to differentiate between the two materials.
  • Heulandite was only recognized as a series in 1997, unlike Stilbite which gained that status back in the early 1800s.

What Are Stilbites and Heulandites Used For?

  • Though some disagree and there is little scientific evidence to support this, Heulandite is thought to relax the nervous system, relieve anxiety, as well as improve cognitive skills and mental clarity.
  • As for Stilbite, it is said to contain anti-inflammatory properties, help to get rid of free radicals in the body, alleviate poisoning symptoms, and treat oral problems such as a loss of taste.
  • The Federal Drug Administration (FDA) has certified zeolite as “Generally Regarded As Safe” (GRAS) for human ingestion and has been used commercially for purifying water for several years. The majority of published studies indicate that zeolite can remove toxic metals and other contaminants from polluted water.

Before you try either of these stones for health or healing, we recommend that you do your own research. We have not used either of these minerals for any of these purposes.

Where Are Stilbite And Heulandite Found?

The volcanic rocks of Iceland, the Faroe Islands, the Isle of Skye, the Fundy Bay, in Nova Scotia, Canada (it is considered the regional mineral there), north of New Jersey, and North Carolina are rich in stilbite.

Heulandite is present in granites, pegmatites, and basalts, along with other zeolite minerals, filling cavities. Berufjördhur, Iceland; islands near Bombay; the Faroe Islands; and northeastern New Jersey are all common occurrences.

Stilbite Crystal Habits

You will find flattened or tabular single crystals containing a sharp termination in most cases.

Single individual crystals, on the other hand, are extremely rare; crystals are commonly found in platy aggregates or unique bent quantities of fan or wheatsheaf pattern stacks, as well as in special “bow-tie” arrangements.

Glistening crystals, globular crystals, bladed groups, circular balls of glowing crystals, and fibrous crystals are also found. Double-terminated crystals are common, and aggregates can be twinned in fascinating bisecting patterns.

Heulandite Crystal Habits

Crystals, as these are typically tabular, have a distinctive shape that resembles an old coffin, with a broader base, thinner sides, and a smooth top and bottom.

Typically, crystals grow in circular aggregates of similar crystals.

Crystals might also have a barrel form, found in clusters of dense, glowing crystals, fan or saddle-shaped, chisel-like tip, found in foliated groups, in rosettes, and grainy.

Often found in geode-like structures and lengthened interesting connected groups of crystals.

Heulandite and Stilbite Properties

Monoclinic crystals are those that have only one face.

They may have a coffin-like habit, but they might also create simple rhombic prisms.

A shell of fine crystals can sometimes grow just with the edges of the rhombs noticeable, giving the crystals the appearance of wedges.

They have a natural cleavage similar to the plane of symmetry, with a pearly lustre on some faces and a vitreous lustre on others.

The mineral is normally colorless or white, but due to inclusions of celadonite, it may be orange, brown, purple, brick-red, or green. It ranges in transparency from clear to translucent. Brewsterite, a strontium and barium zeolite, is isomorphous with heulandite.

The absolute gravity is 2.2, and the Mohs hardness is 3-4.

Stilbite and heulandite are related minerals.

The extreme positive bisectrix of it’s optic axes appears vertical to the cleavage in heulandite, allowing the two minerals to be easily separated.

Conclusion

There are more similarities than differences between Heulandite and Stilbite crystals.

Overall, they both come from the same environments and are very valuable for getting rid of ammonia and other toxic properties.

However, Stilbite is the secondary mineral.

Interested in learning more about unique rocks and minerals like chryscolla, turkey fat mineral, or velvet malachite? You can also check out our blog for our latest articles.