THE MINERAL HEMIMORPHITE
- Chemistry: Zn4 Si2 O7 (OH)2 -H2O, Hydrated Zinc Silicate Hydroxide.
- Class: Silicates
- Subclass: Sorosilicates
- Uses: minor ore of zinc
Specimens
Hemimorphite was originally named calamine but this name had been used for another mineral and hemimorphite was proposed and is now in wide spread use. The hemi means half while the morph means shape and thus hemimorphite is aptly named. Only a few other minerals show hemimorphic character such as tourmaline, but none show it as well as hemimorphite. Clusters of hemimorphite that show well shaped crystals do not always show the hemimorphic character. Because the crystals of a single specimen tend to grow outward with either the "top" or the "bottom" as the overall orientation for that specimen. In order to see the hemimorphic character either a doubly terminated specimen is necessary or two different clusters with different orientations will be needed.
Specimens of hemimorphite tend to be of two very different forms (seems like a trend with this mineral). One form produces very glassy, clear or white, thin, bladed crystals, often well formed showing many crystal faces. Many times these crystals are arranged in fan shaped aggregates. The other form produces a blue to blue-green botryoidal crust that resembles smithsonite or prehnite. Prehnite has a lower density and is usually greener and has different associations with other minerals. Smithsonite has a shimering luster that causes a play of light across the rounded surfaces and has a higher density that hemimorphite. Often hemimorphite will show rough crystal ridges or "cock's comb" structures over top of the basic botryoidal crust. For a collector both forms are a must in their mineral collections.
PHYSICAL CHARACTERISTICS:
- Color is blue-green, green, white, colorless, brown and yellow.
- Luster is vitreous in large crystals to dull in more compact forms.
- Transparency crystals are transparent to translucent.
- Crystal System is orthorhombic; mm2
- Crystal Habits include the bladed crystal form and the botryoidal form as the most common. The crystals are usually elongated and flat. The terminations are different at each end. One termination is blunted by a pedion face that is usually bevelled by several dome faces. The other end is pointed, being capped by a pyramid. The other common form is botryoidal producing a grape bunch texture. Often the botryoidal form has a cock's comb appearance showing rough crystal terminations.
- Cleavage is perfect in one direction.
- Fracture is conchoidal to subconchoidal.
- Hardness is slightly less than 5.
- Specific Gravity is approximately 3.4+ (above average)
- Streak is white.
- Associated Minerals include limonite, aurichalcite, calcite and smithsonite.
- Other Characteristics: strongly pyroelectric and piezoelectric.
- Notable Occurrences include Santa Eulalia and Mapimi, Mexico; New Mexico and New Jersey, USA: England and Zambia.
- Best Field Indicators are crystal habit, color, density and luster.
 Amethyst Galleries' Mineral Gallery MINERALS |
HEMIMORPHITE specimen hmi-1
$ 25.00
$ 25.00
Dims: 1-1/2" x 1-1/2" x 1"
Wt: 15.7 g
Ojuela Mine, Mapimi, Durango, Mexico
This specimen basically is one busy cluster of Hemimorphite crystals with a small amount of limonite matrix. There are a few dozen crystals that range in size from 1/8" to 5/8" in length. They are all coloress, though translucent, and have limonite stains on them. All occur in a flat, bladed prismatic form with a shallow basal pinacoid termination. There is some noticeable damage, but not much, surprisingly.
hmi-1 ($ 25.00)
Ojuela Mine, Mapimi, Durango, Mexico
HEMIMORPHITE specimen hmi-2
$ 40.00
$ 40.00
Dims: 5-1/2" x 3-1/2" x 1"
Wt: 9.9 oz
Mapimi, Durango, Mexico
Several clusters of colorless, bladed Hemimorphite crystals infest the hollow in the limonite host rock of this specimen. Each crystal has a "spearhead" shape and measures from less than 1/8 inch to over 1/2 inch. Individually, they are transparent, but heavy striations on each crystal make the clusters appear white in color. Their luster is more pearly than vitreous. There is surprisingly little damage to the cluster, as it is mostly quite exposed. The limonite matrix is, well, limonite, so it is a bit messy to handle with bare hands. There are some very small calcite crystals in hollows on its underside.
hmi-2 ($ 40.00)
Mapimi, Durango, Mexico
HEMIMORPHITE specimen hmi-3$ 150.00
Dims: 3.0" x 2.7" x 2.7"(7.6 x 6.9 x 6.9 cm)
Wt: 15.8 oz.(449 g)
Yunnan Province, China
One of the most impressive Hemimorphite specimens that I have come across, this specimem is made up of almost half of the mineral by weight. It occurs in the form of a very thick crust that is pale blue in coloration. It shows much breakage along its edges and considerable damage to the top of the crust, but has a large area of undamaged surface with a beatiful sparkly sheen. It is translucent and its compact, radial habit shows well in many parts of the crust's edge. The base rock is made up of a combination of quartz and a powdery red substance that I can't identify. Even with the substantial damage that it has, this specimen is exceedingly pretty, and represents a quality of Hemimorphite that I have rarely seen.
hmi-3 ($150.00)Yunnan Province, China
HEMIMORPHITE specimen hmi-4
$ 35.00
$ 35.00
Dims: 2.6" x 1.9" x 1.7" (6.6 x 4.8 x 4.3 cm)
Wt: 4.4 oz. (125.2 g)
Mapimi, Durango, Mexico
This small hand specimen consists of several clusters of radiating Hemimorphite blades that rest in a shallow hollow in a goethite and limonite host rock. The largest of these clusters has dimensions of 0.6 x 0.4 x 0.3" (1.5 x 1.0 x 0.8 cm) and is in fair condition, as several of its blades are broken and incomplete. One of the other clusters is also mostly incomplete. The crystals that are intact, however, have excellent orthorhombic bladed form, with sharp edges and clean faces that possess a bright pearly luster. All are colorless, transparent, and due to their thinness, very clear. Their average length is between 0.3" and 0.4" (8 and 10 mm) The hollow in which they rest is lined with smaller Hemimorphite blades and what appear to be some tiny rhombohedral calcites. Under these is a pale green conichalcite crust that coats the hollow's surface. This crust has a matte luster and shows tiny reniform or botryoidal formations that are mostly coated by the calcite and hemimorphite. There are a few other, smaller hollows in the host rock that also contain the aforementioned minerals, but most of the crystals therein are damaged and/or incomplete.
hmi-4 ($ 35.00)
Mapimi, Durango, Mexico
HEMIMORPHITE specimen hmi-5
$ 40.00
$ 40.00
Dims: 4.5 x 3.4 x 3.4" (11.4 x 8.6 x 8.6 cm)
Wt: 1 lb., 7.1 oz. (657.0 g)
Durango, Mexico
Several reniform Hemimorphite crusts partly coat the crevices in and the surface of the dull, pale brown host rock of this large hand specimen. Individual nodules of the mineral do not exceed 0.2" (5 mm), and all are generally in excellent condition, as most are sheltered in concave depressions and deep crevices. The material has a pale blue coloration and a luster that ranges from matte to waxy, and sometimes approaches that of reniform smithsonite; it is definitely translucent. Close examination of the broken edges of the crusts allow one to see the compact, fibrous and radial habit of this material. A few clusters of tiny, white Hemimorphite crystals rest on some of the crusts.
hmi-5 ($ 40.00)
Durango, Mexico
HEMIMORPHITE specimen hmi-6
$ 45.00
$ 45.00
Dims: 5.0 x 4.1 x 3.4" (12.7 x 10.4 x 8.6 cm)
Wt: 1 lb., 12.7 oz. (813 g)
Durango, Mexico
This hand specimen consists of several reniform Hemimorphite crusts that have coated hollows in what appears to be a gray igneous host rock. The crusts are generally in good condition, though there is a considerable amount of breakage present on their most exposed points. All show excellent form in their reniform habit, however, and possess a dull waxy luster. The broken surfaces allow one to see the compact, fibrous and radiating habit that forms the reniform crusts, and a few areas show slight layering of material. Their coloration is generally pale blue, though substantial portions of some crusts have a dark gray coloration. A few very exposed nodules show moderate translucence, but the rest of the material is basically opaque due to its coating the dull gray base rock.
hmi-6 ($ 45.00)
Durango, Mexico
HEMIMORPHITE specimen hmi-7
$ 75.00
$ 75.00
Dims: 7.0 x 5.2 x 2.9" (17.8 x 13.2 x 7.4 cm)
Wt: 2 lbs., 3.7 oz. (1.013 kg)
Durango, Mexico
This small cabinet specimen consists of a several druses of reniform Hemimorphite that coat most of a crumbly, pale brown host rock. These druses are generally in good condition, as there is extensive minor damage visible throughout. The reniform habit of the crusts is rather rough, and in some areas there are actually small, bladed crystals that did not form nodules. All have a dull pale-blue coloration and a waxy luster. The Hemimorphite is generally translucent, though some areas appear to be nearly dimly transparent. Thin, intersecting blades of either the host rock or some other material must have formed first, and then the Hemimorphite coated them over, taking on their shape.
hmi-7 ($ 75.00)
Durango, Mexico
HEMIMORPHITE specimen hmi-8
$ 25.00
$ 25.00
Dims: 1.4 x 1.0 x 0.9" (3.6 x 2.5 x 2.3 cm)
Wt: 1.32 oz. (37.5 g) w/ base
Mapimi, Durango, Mexico
A cluster of heavily-intergrown Hemimorphite blades makes up this large thumbnail specimen. These crystals are in excellent condition, showing no detectable damage, and have very good orthorhombic form, considering their intergrowth. All are colorless, translucent to dimly transparent, and show a pearly luster. A small amount of powdery limonite is attached to the cluster, which is hot-glued to an acrylic base.
hmi-8 ($ 25.00)
Mapimi, Durango, Mexico
HEMIMORPHITE specimen hmi-9
$ 25.00
$ 25.00
Dims: 1.7 x 0.7 x 0.5" (4.2 x 1.8 x 1.3 cm)
Wt: 2.9 oz. (83 g) w/ base
El Potosi Mine, Santa Eulalia, Chihuahua, Mexico
A cluster of several intersecting Hemimorphite crystals makes up this specimen. These crystals are some of the largest Hemimorphites that I have seen- one reaches nearly 1.5" (3.8 cm) in length. All are in excellent condition and show reasonably good orthorhombic form, though the larger crystals tend to be somewhat disseminated. They have the standard colorlessness and bright pearly luster of prismatic Hemimorphite, and are transparent only at their terminations- the remainders of their lengths are cloudy. Only a tiny amount of the goethite/limonite base is present, and the piece is hot-glued onto a flat, square acrylic base.
hmi-9 ($ 25.00)
El Potosi Mine, Santa Eulalia, Chihuahua, Mexico
HEMIMORPHITE specimen hmi-10
$ 36.00
$ 36.00
Dims: 2.7 x 2.0 x 1.8" (6.9 x 5.0 x 4.5 cm)
Wt: 5.2 oz. (146 g)
Mapimi, Durango, Mexico
This hand specimen consists of a crust made up of intergrown, fan-shaped Hemimorphite aggregates that partly covers a goethite/limonite host rock. Most of the aggregates are very small, but one in particular is much larger than the rest, having dimensions of 0.9 x 0.5 x 0.4" (2.3 x 1.3 x 0.9 cm). Though it is also the most exposed aggregate, it is in excellent condition, showing no damage. Though the crystals therein are heavily intergrown, they appear to have very good orthorhombic bladed form. They are colorless and translucent, and have a milky-white color and a bright, vitreous luster- most of the smaller clusters, however, are noticeably transparent.
hmi-10 ($ 36.00)
Mapimi, Durango, Mexico
HEMIMORPHITE specimen hmi-11
$ 45.00
$ 45.00
Dims:1.8x1.5x0.9" (4.6x3.8x2.3 cm)
Wt: 1.3oz. (38g)
Santa Eulalia, Chihuahua, Mexico
This is a large spray of hemimorphite crystals in a cavity of a limonite/goethite matrix. These crystals reach 1.7" (4.3cm) in length. Although some of the crystals have abraded tips, others show excellent terminations. Some of the smaller crystals are water-clear and gemmy.
hmi-11 ($ 45.00)
Santa Eulalia, Chihuahua, Mexico
HEMIMORPHITE specimen hmi-12
$ 300.00
$ 300.00
Dims: 4.56x2.14x1.88" (11.58x5.43x4.78cm)
Wt: 12.84oz (363.5g)
Yunnan Province, China
This stalactite is composed entirely of hemimorphite. Most of the specimen is a lovely aqua-blue, although it gets more pale, ultimately colorless, towards the tip. It has an odd appearance that indicates that the stalactite has two growth directions, which generally results from a rock fall in a cave. The growth prior to the angle change is the aqua blue, and afterwards is the pale or colorless growth. There is no indication of crystalline growth on the blue portions, but many crystal facets can be seen on the colorless parts.
hmi-12 ($300.00)
Yunnan Province, China
HEMIMORPHITE specimen hmi-13
$ 68.00
$ 68.00
Dims: 3.24x1.96x1.14" (8.23x4.99x2.90cm)
Wt: 3.53oz (100.0g)
79 Mine, Gila County, Arizona, USA
While this specimen is mostly hemimorphite, there are many other minerals present. The hemimorphite crystals are colorless and transparent, organized in radial clusters of tabular crystals. Most of the clusters have white tops, which looks to me like more hemimorphite that is white and translucent organized in books of thin curved crystals (although I have seen gypsum crystals look like these, too). The color of this specimen comes from two copper minerals that I have not identified, a deep green mineral that forms tiny balls, generally clustered together into a micro-botryoidal crust (possibly brochantite), and a light blue mineral the color of chrysocola but forming tiny fuzzy clumps.
hmi-13 ($ 68.00)
79 Mine, Gila County, Arizona, USA
HEMIMORPHITE specimen hmi-16
$ 25.00
$ 25.00
Dims: 2.11x1.37x1.29" (5.36x3.47x3.28cm)
Wt: 1.90oz (53.8g)
El Potosi Mine, Santa Eulalia district, Mexico
This specimen displays several criss-crossed sprays of translucent white hemimorphite crystals, plus a few smaller transparent colorless ones. Each crystal tapers larger towards its top, which ends with a roof termination. The crystals are strongly striated, and their bases are gray, looking like a black inclusion lies within.
hmi-16 ($ 25.00)
El Potosi Mine, Santa Eulalia district, Mexico
HEMIMORPHITE specimen hmi-15
$ 40.00
$ 40.00
Dims: 3.63x2.74x2.68" (9.21x6.95x6.80cm)
Wt: 11.47oz (325g)
Level 14, Potosi Mine, Santa Eulalia, Mexico
This hemimorphite specimen looks a lot like a gray smithsonite over limonite. However, there is no indication of a "melted wax" luster. A loupe reveals the crystal structure along the edges of the mineral, and the crystals are clearly hemimorphite in the form of transparent and individually colorless crystals with a radial growth habit, intergrown to form a nearly continuous crust about 2 to 3 milimeters thick. The gray color may be due to a thin layer at the top of the crust (basically a coating over the hemimorphite), or perhaps it is just an optical effect. In any case, the sides look white and the top looks gray. The host rock is coplex, primarily consisting of limonite, but also containing many other minerals which I have not tried to identify.
hmi-15 ($ 40.00)
Level 14, Potosi Mine, Santa Eulalia, Mexico