HEULANDITE
Specimen heu-18

Dims: 3.4" x 2.9" x 1.9"(8.6 x 7.4 x 4.8 cm)

Wt: 10.43 oz.(295.6 g)

Poona, India

These are easily the largest Heulandite crystals that I have ever seen. There are two of them laying atop a bed made up of thousands more microscopic crystals. The larger ones, however, are quite visible, with each measuring about 1.5 x 0.8 x 0.5"(3.8 x 2.0 x 1.3 cm). They both have a white coloration and pearly luster, and show small amounts of transparence. They each have very small amounts of damage and exhibit a perfect cleavage in one direction, as shown by the parallel internal fractures that run completely through the crystals. Their forms show a definite monoclinic habit. They and their tiny relatives rest on a matrix of basalt. I never thought that I would see Heulandites this large!

Dims: 3.0" x 2.1" x 2.0"(7.6 x 5.3 x 5.1 cm)

Wt: 2.36 oz.(67.1 g)

Nasik, India

This specimen is one of the most beautiful India zeolite examples that I have seen. It consists of several large, pale orange Heulandite crystals resting on a base of microcrystalline quartz(chalcedony) that is coated with a fine druze and has a dull green coloration. The Heulandite clusters range in length from 0.4 to 1.7"(1.0 to 4.3 cm) and have excellent form, a pearly luster, and are translucent- two of the smallest clusters actually show areas of transparence with good clarity. The chalcedony base appears to be colored green by the presence of a chlorite-rich layer just below the drusy outer layer. It has some spectacular stalactitic formations reminiscent of wax that cools as it drips down a candle. There are also a few small stilbite crystals among the much larger Heulandites, and a small portion of the original basalt base rock on the underside of the piece. I am very attracted to this specimen!

Dims: 2.7" x 2.0" x 1.8"(6.9 x 5.1 x 4.8 cm)

Wt: 3.60 oz.(102.2 g)

Poona, India

This specimen has unusually large Heulandite clusters. They have the standard diamond-shaped tabular form and are pressed together into stacked clusters. They are colorless, have a pearly luster on their main pinacoidal faces and a vitreous luster on their other faces, and are transparent, but have many inclusions and cleavage planes that interrupt ones view. Portions of the largest cluster, which measures 1.8"(4.6 cm) long and 1.4"(3.6 cm) thick, are enveloped by a thin coating of the basalt host. Portions of another cluster are visible opposite the exposed ones on the specimen.

Dims: 1.5" x 1.0" x 0.9"(3.8 x 2.5 x 2.3 cm)

Wt: 21.9 g

Malagaon, India

I think that David, who writes the general mineral descriptions, will be quite interested in this specimen. It solely consists of an intergrown aggregate of Heulandite crystals with a curved, s-shaped form, pearly luster, and very strange green color. I have no idea what might cause such a color in Heulandite! It shows translucence around its edges and one small area of definite transparence on one prism face. The cluster has two tiny spots of damage, at least one of which must be where the specimen was attached to its host rock. This is by far the weirdest zeolite that I have seen yet.

Dims: 1.9" x 1.4" x 1.3"(4.8 x 3.6 x 3.3 cm)

Wt: 1.27 oz.(36.0 g)

Malagaon, India

This specimen is composed of an aggregate of Heulandite that has a very odd green color. The crystals are translucent around their edges, have a pearly luster, and good, curved crystal form with considerable damage. A small amount of some weathered material rests near one of the breaks; I cannot tell exactly what it is. In one area of the aggregate, some of the Heulandite fades to a more common white coloration with a hint of brown. It is truly a bizarre piece of material.

Dims: 3.2" x 2.0" x 1.5"(8.1 x 5.1 x 3.8 cm)

Wt: 3.12 oz.(88.4 g)

Poona, India

This specimen is made up of a few aggregates of dark brown Heulandite crystals that rest amid a cluster of apophyllites on a quartz crust that covers a base of basalt. The largest aggregate measures 1.0 x 0.8 x 0.6"(2.5 x 2.0 x 1.5 cm), whereas the next smallest is about half that size. All have a pearly luster on their basal faces, a waxy luster on their prism faces, and are almost thoroughly opaque. The apophyllite crystals around them are colorless, transparent and quite clear, and have a vitreous luster and excellent tetragonal prismatic crystal form. They reach a maximum size of 1.5 x 1.1 x 0.8"(3.8 x 2.8 x 2.0 cm). Neither the Heulandites nor the apophyllites show much damage, which is mostly confined to the edges of the specimen. I have never seen Heulandite occur in this dark brown color before; I could only guess about the inclusion that gives it that color.

Dims: 3.2" x 3.5" x 1.5"(8.1 x 8.9 x 3.8 cm)

Wt: 8.68 oz.(246.1 g)

Nasik, India

A thick crust made up of hundreds of pale orange Heulandite crystals coats the basalt base of this specimen. These crystals occur as tabular crystals with a diamond-shaped cross-section and measure 0.3 - 0.4"(0.8 - 1.0 cm) on average. There is a large amount of damage to the crust, but the majority of the crystals are in good condition. They have a pearly luster and are translucent, with a few crystals exhibiting dim transparence. The basalt host rock is thinner than it appears, and is heavily infused with more Heulandite. It is a pretty specimen.

Dims: 6.7" x 5.9" x 3.5" (17.0 x 15.0 x 8.9 cm)

Wt: 3 lbs., 8.6 oz.(1.605 kg)

Poona, India

I have always liked this specimen immensely. It is in the form of a geode, wherein the vug that formed inside the basalt host rock was carved out almost completely, leaving a basalt "skin" around the hollow, which is visible from holes at opposite ends of the vug. The hollow itself is lined with a layer of mammillary, white agate which is in turn coated with countless tiny, transparent quartz crystals. Close examination will reveal a few tiny, pale-green, globular prehnite aggregates. Howeverr, the Heulandite crystals that are clustered together near the smaller hole in the vug are quite visible. They have a creamy, off-white coloration, a pearly luster, and are translucent. They occur as aggregates of thin, tabular crystals with a diamond-shaped cross-section, and show no damage, as they are well protected inside the deep vug. It is a beautiful specimen that balances in a perfect position for display (I would hot-glue it to a base for added stability, though).

Dims: 3.3" x 2.7" x 2.1" (8.4 x 6.9 x 5.3 cm)

Wt: 11.0 oz. (311 g)

Poona, India

A rather simple specimen, this piece consists of a section of the inside of a basalt vug that is lined with many pale orange aggregates of Heulandite crystals. These aggregates so not exceed 0.3" (8 mm) in any dimension and have a rather rounded, worn form that makes it difficult to determine the crystals' bladed form. Their pale orange color deepens towards the host rock, and seems to be somewhat directional. The crystals have a pearly to waxy luster and are dimly translucent. Among them rest a few aggregates of stilbite that have good form, a pearly luster, and are quite translucent. A few stilbite aggregates along one edge of the piece are broken, but all the other material on the base rock seems to be in good condition.

Dims: 2.5 x 1.7 x 1.1" (6.4 x 4.3 x 2.8 cm)

Wt: 1.79 oz. (50.9 g)

Jalgaon, India

Several "sheaves" of slightly radiating Heulandite crystals make up this small hand specimen. The crystals are stacked back-to-back, with several in each sheaf. The largest of these sheaves has dimensions of 0.7 x 0.5 x 0.5" (1.8 x 1.3 x 1.3 cm), and almost all are in excellent condition, as only one or two sheaves are visibly damaged. Their monoclinic bladed form is very good, with well-defined edges and clean faces that possess a bright pearly-to-vitreous luster. All have a pale, rusty-red coloration and are transparent and dimly clear due to various internal fractures and cloudy inclusions. The Heulandites rest on a very thin basalt crust that is coated with a druse of tiny quartz crystals. Part of a thin, stalactitic formation is attached to the cluster, consisting of a very small basalt core and a much thicker crystalline quartz "skin". All of these quartz crystals are in ver good condition, and all are colorless, transparent, and quite clear.

Dims: 2.6 x 1.6 x 1.5" (6.6 x 4.1 x 3.8 cm)

Wt: 1.75 oz. (49.7 g)

Jalgaon, India

A single Heulandite crystal rests in the basalt vug that makes up the base of this specimen. This crystal is in fair to poor condition, as it is heavily damaged and broken at one end. However, it has excellent monoclinic bladed form, and appears to be made up many thinner blades that are stacked together. It is colorless, dimly transparent and cloudy, and has the standard pearly luster. The vug in which the Heulandite crystal rests is lined with a thin druse of tiny, transparent quartz crystals. This druse takes on an almost botryoidal shape in some areas and coats a very thin stalactite that almost intersects the Heulandite crystal.

Dims: 3.9 x 2.5 x 1.4" (9.9 x 6.4 x 3.6 cm)

Wt: 4.75 oz. (134.7 g)

Poona, Maharashtra State, India

A crust made up of scores of intergrown Heulandite crystals lines a vug in the basalt base of this specimen. Though they do not exceed 0.3" (8 mm) in length, all but a few are undamaged and in excellent condition. Their small size and heavy intergrowth make their monoclinic bladed form a bit difficult to study, but appears to be quite good. All have a pale to moderate rust-red coloration due to some form of included material that I cannot identify. They are translucent and possess the standard pearly luster.

Dims: 3.9 x 2.6 x 1.3" (9.9 x 6.6 x 3.3 cm)

Wt: 7.24 oz. (205.2 g)

Poona, Maharashtra State, India

A crust made up of scores of intergrown Heulandites coats part of the basalt base of this piece. These crystals are in very good condition- only a few are damaged- but do not exceed 0.3" (8 mm) in length, width, or thickness. All are rather heavily intergrown but appear to have very good monoclinic bladed form, with well-defined edges and clean faces. Their normally white color is strongly tinted by a rust-red dust that coats them and may be slightly included. All are translucent at best and possess a pearly luster.

Dims: 5.1 x 4.0 x 2.3" (13.0 x 10.2 x 5.8 cm)

Wt: 1 lb., 2.0 oz. (509 g)

Poona, Maharashtra State, India

Several clusters of curved Heulandite blades rest on the basalt base of this specimen. These clustersreach dimensions of 1.8 x 0.9 x 0.5" (4.6 x 2.3 x 1.3 cm) and are generally in good condition, though the 2 largest clusters are noticeably damaged. Those that are not, however, contain blades that have excellent monoclinic prismatic form. They have well-defined edges and clean faces that possess the standard bright pearly luster. They have a milky-white coloration and are generally translucent, though a few show noticeable clarity. However, a few of the clusters have a greenish tinge caused by another mineral (a chlorite mineral, perhaps?). The Heulandites are accompanied by a single prehnite nodule and rest on a druse that appears to be made up of countless tiny stilbites that are also tinted green. A few patches of the Heulandite appear to be compact and fibrous, and extend in veins a short way into the basalt base.

Dims: 2.4 x 2.2 x 1.6" (7.4 x 5.6 x 4.1 cm)

Wt: 4.70 oz. (133.2 g)

Poona, Maharashtra State, India

At least 10 aggregated Heulandite "books" rest on the basalt base of this hand specimen. Only one of these books exceeds 0.2" (5 mm) in length or width, and it measures 1.1 x 0.5 x 0.5" (2.6 x 1.3 x 1.2 cm). One of the small books is broken and incomplete, but the rest are intact and in excellent condition, showing excellent monoclinic form and a somewhat bladed habit. All have an uneven, pale red-brown coloration with a faint maroon tinge and a bright, pearly-to-vitreous luster, and are dimly transparent due to countless cloudy inclusions and internal fractures. The basalt base is covered with a thin, white, crystalline quartz crust. This crust contains a few small clusters of more Heulandite aggregates, but they not very noticeable.

Dims: 0.7 x 0.6 x 0.6" (1.7 x 1.5 x 1.5 cm)

Wt: 10 g w/ specimen box

Parana, Brazil

This thumbnail specimen consists of a cluster of tightly-aggregated Heulandite crystals. These crystals are generally in excellent condition and reach lengths of about 0.3" (8 mm). All have excellent monoclinic bladed form, a rather odd, rusty-red coloration and a bright, vitreous luster when viewed edge-on. Exposed faces, however, have a pearly luster. All are dimly transparent, though the cluster as a whole is essentially opaque. It is hot-glued into a plastic specimen box.

Dims:5.2x4.0x3.0" (13.2x10.1x7.6 cm)

Wt: 17.9oz. (507g)

Poona, India

This specimen consists of a cavity in a basalt matrix. This cavity is filled with crystals of heulandite to 1.0" (2.5cm). Stilbite is also present. Also in the cavity are odd-looking stalactites and columns. These are covered with millions of tiny crystals. All in all, this is a very distinctive piece.

Dims: 4.2x1.3x1.8" (10.6x3.2x4.5 cm)

Wt: 2.5 oz. (70.0g)

Sakur, India

This specimen is almost entirely green heulandite. The largest crystals are on top, and pregressively smaller crystals form the base. Examining the bottom, there is a visible blade of a clear colorless mineral (quartz?) that was the initial structure, and the heulandite crystals attached to it are almost a crust - the individual crystals are very fine. The large heulandite crystals are an excellent lime green color, are dimly translucent, and have a vitreous luster.

Dims: 3.49x2.28x1.29" (8.85x5.78x3.28cm)

Wt: 2.77oz (78.3g)

Jalgaon, Mahrashtra, India

This is a very pretty specimen of heulandite. The crystals are colorless and translucent, with a pearly luster. They have a trapezoidal shape with a strong upwards curvature at the ends, as the crystals are thicker there. The backdrop to the heulandite is a fine quartz crystal druze over a green-gray host rock with a small globular habit. The host rock was a hard shell lining a cavity in the original host.

Dims: 5.17x3.81x2.35" (13.12x9.68x5.98cm)

Wt: 22.79oz (646g)

Jalgaon, Mahrashtra, India

This highly aesthetic specimen displays a single large cluster of heulandite against a druze of tiny colorless quartz crystals on a layer of blue agate. The heulandite is slightly pink, has a pearly luster, and contrasts nicely with the slightly bluish-gray druze. A loupe shows that the quartz crystals have an unusual habit: while they do have a (somewhat rounded) hexagonal cross-section, their terminations are stepped and strictly show a 3-sided pyramid. Also, some of the crystals seem almost striated, but I attribute this appearance to the stepped growth pattern. Also, the druze shows a stalactitic form, with two of the stalactities missing their tips. Speaking of damage, there is a tiny amount at the tip of one end of the heulandite.

dims mm=86.70x84.80x53.46

wt g=262

Rats Nest Claim, Challis, Custer Co., Idaho, USA

This is a very nice specimen of heulandite. It is somewhat unusual in that it does not appear to have formed in a cavity in a basalt with associated quartz as is so often the case. Rather, this appears to have been a volcanic tuff with glassy inclusions which altered (likely due to salt water) to heulandite. Many small altered nodules are visible in the matrix, although the bulk of the heulandite has been exposed on the surface, itself once a larger glassy nodule. The large pink heulandite crystals rest upon a layer of a white tough but feathery looking layer of mordenite.