CINNABAR (Mercury Sulfide) Minerals | by Name | by Class | by Groupings | Search

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THE MINERAL CINNABAR

● Chemistry: HgS, Mercury Sulfide ● Class: Sulfides and Sulfosalts ● Uses: primary ore of mercury, a pigment and as a minerals specimen. ● Specimens Cinnabar is a colorful mineral that adds a unique color to the mineral color palette. Its cinnamon to scarlet red color can be very attractive. Well shaped crystals are uncommon and the twinned crystals are considered classics among collectors. The twinning in cinnabar is distinctive and forms a penetration twin that is ridged with six ridges surrounding the point of a pryamid. It could be thought of as two scalahedral crystals grown together with one crystal going the opposite way of the other crystal. Cinnabar was mined by the Roman Empire for its mercury content and it has been the main ore of mercury throughout the centuries. Some mines used by the Romans are still being mined today. Cinnabar shares the same symmetry class with quartz but the two form different crystal habits. PHYSICAL CHARACTERISTICS:

● Color is a bright scarlet or cinnamon red to a brick red. ● Luster is adamantine to submetallic in darker specimens. ● Transparency crystals are translucent to transparent. ● Crystal System is trigonal; 32 ● Crystal Habits: individual, well formed, large crystals are scarce; crusts and crystal complexes are more common; may be massive, or in capilary needles. Crystals that are found tend to be the six sided trigonal scalahedrons that appear to have opposing three sided pyramids. It also forms modified rhombohedrons, prismatic and twinned crystals as discribed above. ● Cleavage is perfect in three directions, forming prisms. ● Fracture is uneven to splintery. ● Hardness is 2 - 2.5. ● Specific Gravity is approximately 8.1+ (very heavy for a non-metallic mineral) ● Streak is red ● Associated Minerals are realgar, pyrite, dolomite, quartz, stibnite and mercury. ● Other Characteristics: silghtly sectile and crystals can be striated. ● Notable Occurances include Almaden, Spain; Idria, Serbia; Hunan Prov., China and California, Oregon, Texas, and Arkansas, USA.

http://mineral.galleries.com/minerals/sulfides/cinnabar/cinnabar.htm (1 of 2) [8/2/2001 2:51:56 PM] CINNABAR (Mercury Sulfide) ● Best Field Indicators are crystal habit, density, cleavage, softness and color.

http://mineral.galleries.com/minerals/sulfides/cinnabar/cinnabar.htm (2 of 2) [8/2/2001 2:51:56 PM] Amethyst Galleries' Mineral Gallery

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MINERALS The Mineral Gallery is a constantly growing collection of mineral descriptions, images, and specimens (see our new specimens last updated By Name 25-May-2001, and What's New last updated 02-Dec-2000), together with A list of minerals in alphabetical order several ways of accessing these descriptions. The descriptions include searchable mineralogical data, plus other information of interest to students By Class and rock hounds! The inline GIF images (size about 10k) usually are linked Elements, Oxides, to larger JPEG images (size about 50k). Carbonates, etc. To purchase our specimens, select a mineral using any of the indexes, and Interesting Groupings then choose the Specimens link (or use the specimens shortcut on the Gemstones, Birthstones, By_Name index). This will usually display several available specimens, etc. some of which may be marked Sold or Sale Pending, but others will have an Order link which will add that specimen to your currently pending order. Full Text Search You may Cancel or Complete your order then, or after further browsing. Mineral identification by Generally, you will return here to review your order (if any), and from keyword searching there you will Cancel or Complete it. Shipping is normally the next business day (with 3 to 5 days delivery time for most North America destinations). For more information (including our address), see the page How to Buy also browse our From Us. Gift Gallery and our Do you have comments, suggestions, or requests about this service? Jewelry Gallery Please provide us with feedback; we would appreciate it! Our phone number is (937)266-7625. You may also contact us by e-mail as follows: ● specimens or sales info: [email protected] ● mineralogical questions or comments: [email protected] ● comments for the owners: [email protected] ● comments for the webmaster: [email protected]

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http://mineral.galleries.com/default.htm (1 of 2) [8/2/2001 2:51:58 PM] Amethyst Galleries' Mineral Gallery page! Amethyst Galleries is not just about Minerals anymore! Here is our List of Galleries Minerals (that's this page) Southwestern Contemporary Sterling Silver Jewelry Gifts (including bookends made from agate and other minerals) Copyright ©1995-1998 by Amethyst Galleries, Inc. Unless otherwise noted, all descriptions, images, and programs are the property of Amethyst Galleries, Inc., and may not be copied for commercial purposes. Permission to copy descriptions and images is granted for personal and educational use only. All such copies must include this copyright notice and explicit references to this URL.

http://mineral.galleries.com/default.htm (2 of 2) [8/2/2001 2:51:58 PM] Minerals by Name Minerals | By_Class | By_Groupings | Search Minerals by Name A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Choose a letter of the alphabet from the above list, and the minerals will be listed that begin with that letter. The mineral name itself is a link to the description of that mineral species, while the number to the left is the approximate count of the number of specimens currently available for sale of that species, and is also a direct link to the list of specimens. The count may be zero, but if the link is active then there are specimens available to view, just not currently for sale. If the count is zero and the link is not active, then there are not even any specimens in the database. Remember, there may be more than one page of specimens, so you may need to select Next Page one or more times to see the entire list of available specimens.

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http://mineral.galleries.com/minerals/by-name.htm [8/2/2001 2:51:58 PM] The Mineral Gallery - Minerals by Class Minerals By Class Minerals can be organized, mainly according to their chemistry, into the following classes

MINERALS ● Elements Class: The Metals and their alloys and the Nonmetals. By Name ● Sulfides Class: The Sulfides, the Selenides, the Tellurides, the A list of minerals in Arsenides, the Antimonides, the Bismuthinides and the Sulfosalts. alphabetical order ● Halides Class: The Fluorides, the Chlorides and the Iodides. By Class ● Oxides Class: The Oxides and the Hydroxides. Elements, Oxides, ● Carbonates Class: The Carbonates, the Nitrates and the Borates. Carbonates, etc. ● Sulfates Class: The Sulfates, the Sulfites, the Chromates, the Interesting Groupings Molybdates, the Selenates, the Selenites, the Tellurates, the Tellurites Gemstones, Birthstones, and the Tungstates (or the Wolframates). etc. ● Phosphates Class: The Phosphates, the Arsenates, the Vanadates and Full Text Search the Antimonates. Mineral identification by ● Silicates Class: The Silicates (the largest class). keyword searching ● The Organics Class: The "Minerals" composed of organic chemicals! ● The Mineraloids: The "Minerals" that lack crystal structure!

http://mineral.galleries.com/minerals/by_class.htm [8/2/2001 2:51:59 PM] Mineral Gallery - Interesting Mineral Groupings

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MINERALS ● Birthstones: Lists the commonly recognized birthstones. By Name ● Gemstones: Includes gem varieties of minerals. A list of minerals in ● Biblestones: Minerals referenced in the Bible. alphabetical order ● Significant Element: Includes ores of metals such as lead or By Class Copper. Elements, Oxides, ● Meteoritic Minerals: Minerals found in meteorites. Carbonates, etc. ● Minerals that Twin: These minerals may form twinned crystals. Interesting Groupings ● Fluorescent Minerals: These glow in ultraviolet light. Gemstones, Birthstones, ● Minerals by Locality: Some notable mineral sites and the etc. minerals found there. Full Text Search ● Natural Groupings: Natural associations such as pegmatities, Mineral identification by vugs, etc. keyword searching ● Radioactive Minerals: Minerals that emit high energy radiation. ● Minerals by Class: Elements, Oxides, Silicates, etc. ● Minerals by Name: Alphabetical listing (one very long list, over 50k).

http://mineral.galleries.com/minerals/interest.htm [8/2/2001 2:52:00 PM] Mineral Search Mineral Search

A Glossary of Terms is available which describes the consistent set of terms used in this mineral database, and offers suggestions for effective searching. Try to use several independent descriptive words, since "very heavy" will also match "heavy" and "very soft". Also, don't use negatives (such as "not transparent").

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http://mineral.galleries.com/scripts/search.exe [8/2/2001 2:52:00 PM] The Mineral Gallery - Sulfides Class

The Sulfides Class As well as the Selenides, the Tellurides, the Antimonides, the Arsenides and the Sulfosalts.

MINERALS The members of the Sulfide Class form an economically important class of minerals. Most major ores of important metals such as copper, lead and By Name silver are sulfides. Strong generalities exist in this class. The majority of A list of minerals in sulfides are metallic, opaque, generally sectile, soft to average in hardness alphabetical order and they have high densities, black or dark colored streaks and an igneous By Class origin. But, there are a few vitreous and transparent members such as realgar, cinnabar and orpiment that tend to break the mold, so to speak. Elements, Oxides, Carbonates, etc. Minerals belonging to the selenide, telluride, antimonide and arsenide subclasses have very similar properties to the more common sulfides and are Interesting Groupings thus included here. The whole or partial supplanting of sulfur by either Gemstones, Birthstones, selenium, tellurium, antimony, arsenic or bismuth is possible because these etc. elements have similar sizes, charges and ionic strengths. Only minerals in Full Text Search the sulfide class that have no appreciable sulfur are included in these Mineral identification by subclasses. If there is enough sulfur in the mineral to be named in the keyword searching formula than it is treated as a normal sulfide. Except in the case of the Sulfosalts. This is a large segment of the sulfide class whose difference from the other sulfides lies in the position of the semi-metal ions. In most ordinary sulfides that contain a semi-metal such as antimony, arsenic or bismuth, they substitute in the sulfur positions, but in sulfosalts they substitute for the metal ions and bond with the sulfurs. The term sulfosalts came from a theory that these minerals were the salts of acids in which the oxygens are replaced by sulfurs. Such as Na2SO4 is the salt of H2SO4 or sulfuric acid; then enargite, Cu3AsS4. would be the salt of the hypothetical acid H6AsS4. This theory is not considered credible now but the name "sulfosalt" still persists.

These are some of the members of the Sulfide Class: The Standard Sulfides:

http://mineral.galleries.com/minerals/sulfides/class.htm (1 of 6) [8/2/2001 2:52:03 PM] The Mineral Gallery - Sulfides Class ● Acanthite/Argentite (Silver Sulfide) ● Aguilarite (Silver Selenium Sulfide) ● Alabandite (Manganese Sulfide) ● Argentopentlandite (Silver Iron Nickel Sulfide) ● Argentopyrite (Silver Iron Sulfide) ● Argyrodite (Silver Germanium Sulfide)

● Arsenopyrite (Iron Arsenic Sulfide) ● Bismuthinite (Bismuth Sulfide)

● Bornite (Copper Iron Sulfide) ● Carrollite (Copper Cobalt Nickel Sulfide)

● Chalcocite (Copper Sulfide)

● Chalcopyrite (Copper Iron Sulfide)

● Cinnabar (Mercury Sulfide) ● Cobaltite (Cobalt Arsenic Sulfide) ● Covellite (Copper Sulfide) ● Cubanite (Copper Iron Sulfide) ● Digenite (Copper Sulfide) ● Famatinite (Copper Antimony Sulfide)

● Galena (Lead Sulfide) ● Germanite (Copper Germanium Gallium Iron Zinc Arsenic Sulfide) ● Gersdorffite (Nickel Arsenic Sulfide) ● Glaucodot (Copper Iron Arsenic Sulfide) ● Greenockite (Cadmium Sulfide) ● Hauchecornite (Nickel Bismuth Antimony Sulfide) ● Hauerite (Manganese Sulfide) ● Jalpaite (Silver Copper Sulfide) ● Kermesite (Antimony Oxysulfide) ● Laurite (Ruthenium Sulfide) ● Lautite (Copper Arsenic Sulfide) ● Linnaeite (Cobalt Sulfide)

http://mineral.galleries.com/minerals/sulfides/class.htm (2 of 6) [8/2/2001 2:52:03 PM] The Mineral Gallery - Sulfides Class ● Marcasite (Iron Sulfide) ● Metacinnabar (Mercury Sulfide) ● Millerite (Nickel Sulfide)

● Molybdenite (Molybdenum Sulfide)

● Orpiment (Arsenic Sulfide) ● Patronite (Vanadium Sulfide) ● Pentlandite (Iron Nickel Sulfide) ● Polydymite (Nickel Sulfide)

● Pyrite (Iron Sulfide)

● Pyrrhotite (Iron Sulfide)

● Realgar (Arsenic Sulfide) ● Rheniite (Rhenium Sulfide) ● Schollhornite (Hydrated Sodium Chromium Sulfide) ● Siegenite (Cobalt Nickel Sulfide)

● Sphalerite (Zinc Iron Sulfide) ● Stannite (Copper Iron Tin Sulfide) ● Sternbergite (Silver Iron Sulfide)

● Stibnite (Antimony Sulfide) ● Stromeyerite (Silver Copper Sulfide) ● Teallite (Lead Tin Sulfide) ● Tetradymite (Bismuth Tellurium Sulfide) ● Tungstenite (Tungsten Sulfide) ● Ullmannite (Nickel Antimony Sulfide) ● Wurtzite (Zinc Iron Sulfide)

Subclass: Sulfosalts

● Aikinite (Lead Copper Bismuth Sulfide) ● Andorite (Silver Lead Antimony Sulfide)

http://mineral.galleries.com/minerals/sulfides/class.htm (3 of 6) [8/2/2001 2:52:03 PM] The Mineral Gallery - Sulfides Class ● Baumhauerite (Lead Arsenic Sulfide) ● Berthierite (Iron Antimony Sulfide) ● Boulangerite (Lead Antimony Sulfide) ● Bournonite (Lead Copper Antimony Sulfide) ● Chalcostibite (Copper Antimony Sulfide) ● Cylindrite (Iron Lead Tin Antimony Sulfide) ● Dufrenoysite (Lead Arsenic Sulfide) ● Emplectite (Copper Bismuth Sulfide)

● Enargite (Copper Arsenic Sulfide) ● Franckeite (Lead Tin Iron Antimony Sulfide) ● Freieslebenite (Silver Lead Antimony Sulfide) ● Geocronite (Lead Antimony Arsenic Sulfide) ● Gratonite (Lead Arsenic Sulfide) ● Hutchinsonite (Thallium Lead Arsenic Sulfide)

● Jamesonite (Lead Iron Antimony Sulfide) ● Jordanite (Lead Thallium Arsenic Antimony Sulfide) ● Matildite (Silver Bismuth Sulfide) ● Meneghinite (Copper Lead Antimony Sulfide) ● Miargyrite (Silver Antimony Sulfide) ● Owyheeite (Silver Lead Antimony Sulfide) ● Polybasite (Silver Copper Antimony Sulfide) ● Proustite (Silver Arsenic Sulfide)

● Pyrargyrite (Silver Antimony Sulfide) ● Sartorite (Lead Arsenic Sulfide) ● Schapbachite (Silver Bismuth Sulfide) ● Semseyite (Lead Antimony Sulfide) ● Smithite (Silver Arsenic Sulfide) ● Stephanite (Silver Antimony Sulfide) ● Tennantite (Copper Arsenic Sulfide)

● Tetrahedrite (Copper Iron Antimony Sulfide) ● Wittichenite (Copper Bismuth Sulfide) ● Wittite (Lead Bismuth Selenide Sulfide)

http://mineral.galleries.com/minerals/sulfides/class.htm (4 of 6) [8/2/2001 2:52:03 PM] The Mineral Gallery - Sulfides Class ● Xanthoconite (Silver Arsenic Sulfide) ● Zinkenite (Lead Antimony Sulfide)

Subclass: Selenides*

● Berzelianite (Copper Selenide) ● Clausthalite (Lead Selenide) ● Eucairite (Silver Copper Selenide) ● Klockmannite (Copper Selenide) ● Tiemannite (Mercury Selenide) ● Umangite (Copper Selenide)

Subclass: Tellurides*

● Altaite (Lead Telluride) ● Calaverite (Gold Telluride) ● Coloradoite (Mercury Telluride) ● Empressite (Silver Telluride) ● Hessite (Silver Telluride) ● Kostovite (Copper Gold Telluride) ● Krennerite (Silver Gold Telluride) ● Melonite (Nickel Telluride) ● Nagyagite (Gold Lead Antimony Iron Telluride Sulfide) ● Petzite (Silver Gold Telluride) ● Rickardite (Copper Telluride) ● Sylvanite (Silver Gold Telluride)

Subclass: Antimonides*

● Aurostibite (Gold Antimonide) ● Breithauptite (Nickel Antimonide) ● Dyscrasite (Silver Antimonide)

http://mineral.galleries.com/minerals/sulfides/class.htm (5 of 6) [8/2/2001 2:52:03 PM] The Mineral Gallery - Sulfides Class Subclass: Arsenides*

● Domeykite (Copper Arsenide) ● Lollingite (Iron Arsenide) ● Maucherite (Nickel Arsenide)

● Nickeline (Nickel Arsenide) ● Nickel-skutterudite (chloanthite) (Nickel Arsenide) ● Rammelsbergite (Nickel Arsenide) ● Safflorite (Cobalt Iron Arsenide) ● Skutterudite (Cobalt Arsenide) ● Smaltite (Cobalt Nickel Arsenide) ● Sperrylite (Platinum Arsenide)

* These minerals are sometimes thought of as alloys of metals with semi-metals and placed in the Elements Class.

http://mineral.galleries.com/minerals/sulfides/class.htm (6 of 6) [8/2/2001 2:52:03 PM] http://mineral.galleries.com/minerals/sulfides/cinnabar/cinnabar.jpg

http://mineral.galleries.com/minerals/sulfides/cinnabar/cinnabar.jpg [8/2/2001 2:52:03 PM] Cinnabar Specimens Minerals | By_Name | By_Class | Sulfides | Cinnabar Cinnabar Specimens

This list can be limited to available items only. This is a partial listing. See the Next Page (earlier specimens) # CIN-14, $125.00 Sold! Dims: 2.9 x 1.7 x 1.7" (7.4 x 4.3 x 4.3 cm) .... Wt: 5.8 oz. (163.9 g) .... Loc: Tongren, Guizhou Province, China A single prismatic Cinnabar crystal rests on the gray limestone host rock of this small hand specimen. Though it is trigonal in form, it also is in the form of a penetration twin, so that it appears to have a six-rayed, pentagonal cross-section. It has visible dimensions of 0.5 x 0.2 x 0.2" (1.3 x 0.5 x 0.5 cm) and is in pristine condition, showing no human-induced damage whatsoever. Its form is also excellent, as all edges are sharp and all faces are striated but flat and clean, and possess a bright submetallic luster. Its red coloration is so deep that it is nearly opaque to all intents and purposes, and its metallic luster provides some interference. The crystal rests on a bed of heavily intergrown rhombohedral dolomite crystals and is adjacent to a cluster of small, prismatic quartz crystals (see the close-up image).

# CIN-13, $140.00 Dims: 2.2 x 1.8 x 1.4" (5.6 x 4.6 x 3.6 cm) .... Wt: 4.4 oz. (123.9 g) .... Loc: Tongren, Guizhou Province, China A single, well-formed Cinnabar crystal rests on the dolomite-and-limestone base of this specimen. The crystal has dimensions of 0.6 x 0.3 x 0.3" (1.5 x 0.8 x 0.8 cm), and is in very good condition, showing two small spots of minor damage, one at the base of its termination, and one at its tip. Its trigonal prismatic form is excellent; it occurs in the form of a penetration twin, so that when viewed from above, the termination is in the shape of a six-rayed star (see the close-up image). Though a few are disjointed, most of its surfaces are well-defined and its faces are striated but generally clean, and possess a submetallic and almost adamantine luster. It has the classic deep red coloration of Cinnabar and is translucent under bright light, showing patches of dim transparence in some areas. It rests on a bed of white dolomite that has good rhombohedral form but is heavily damaged, which in turn coats parts of the brown limestone base rock.

# CIN-12, $110.00 Dims: 2.4 x 2.1 x 1.7" (6.1 x 5.3 x 4.3 cm) .... Wt: 3.8 oz. (107.4 g) .... Loc: Tongren, Guizhou Province, China This small hand specimen consists of a single trigonal prismatic Cinnabar crystal that rests on a dolomitic limestone base. It has visible dimensions of 0.5 x 0.2" (1.3 x 0.5 cm) and is in excellent condition- the only noticeable damage appears to be partly healed, and thus occurred prior to the mining of the specimen. Its edges are well-defined and its faces are clean, possessing an adamantine, submetallic luster. It has the standard deep red coloration of this mineral and

http://mineral.galleries.com/scripts/item.exe?LIST+Minerals+Sulfides+Cinnabar (1 of 2) [8/2/2001 2:52:07 PM] Cinnabar Specimens is dimly transparent in halogen light. The crystal extends out of a hollow in the host rock that is line with many small, dull, cream-colored dolomite rhombohedrons and a few tiny quartz crystals. When looking down into the crevice, one can see another, incomplete Cinnabar crystal that is heavily intergrown with both the first crystal and the dolomites. # CIN-11, $90.00 Sold! Dims: 3.3" x 2.9" x 1.8" (9.4 x 7.3 x 4.6 cm) .... Wt: 6.83 oz. (193.7 g) .... Loc: Guizhou Province, China Three undamaged Cinnabar crystals rest on the dolomite-and-limestone host rock of this specimen. The largest of these is also the most exposed, and has dimensions of 0.4 x 0.2 x 0.2" (1.0 x 0.5 x 0.5 cm); the smallest of the crystals is deeply embedded in the dolomite base, and is barely visible. All show excellent trigonal prismatic form; the largest and smallest crystals show flat, basal terminations, whereas the other crystal has a warped form that makes it appear to be nearly octahedral! All have the deep red color that is standard for Cinnabar, and their luster is subadamantine-to-submetallic. Though it is difficult to determine, I am relatively certain that all are transparent and clear. The dolomite crust from which the Cinnabars extend is made up of dull, cream-colored intergrown rhombohedrons with curved edges. They, in turn, rest on a dark gray-brown base of dolomitic limestone. A large piece of a broken quartz crystal also rests on the dolomite crust, and appears to contain several incomplete Cinnabar crystals that were tr This was a partial listing. See the Next Page (earlier items) This list can be limited to available items only. Would you like to be notified when additional specimens are available? Yes Would you like to fill out a special request form? Yes

http://mineral.galleries.com/scripts/item.exe?LIST+Minerals+Sulfides+Cinnabar (2 of 2) [8/2/2001 2:52:07 PM] Mineral Gallery - THE TWINNED MINERALS

The Twinned Minerals

CINNABAR (Penetration Twin) Twinned minerals have their own following in the mineral collecting MINERALS hobby. There are collectors that are only interested in twinned minerals. Twins can add a fascinating side to otherwise boring minerals or can add By Name yet another dimension to an already complex mineral such as calcite. A list of minerals in There are several minerals that form classic twins such as chalcocite, alphabetical order fluorite, sanidine, microcline, harmotome, staurolite, gypsum, cinnabar, By Class spinel and rutile to name a few (more are listed below). Some twins Elements, Oxides, have been given colloquial names such as the "fairy cross", "iron cross" Carbonates, etc. and "cog wheel" twins. Interesting Groupings Twins form as a result of an error during crystallization. Instead of a Gemstones, Birthstones, etc. "normal" single crystal, twins will often appear doubled where two crystals appear to be growing out of or into each other, like Siamese Full Text Search twins. Some twins however are not even identifiable outwardly and Mineral identification by some minerals in fact have been found to be just a twinned variety of keyword searching another mineral. Accidental relationships are not considered twins, such as when two distinct crystals grow more or less randomly side-by-side Physical Properties or toward each other, etc. Also epitaxial overgrowths are also not twins. Keys to identifying minerals These occur when one mineral of similar structure, but different chemistry, grows onto and "continues" the earlier mineral's crystal. A twin's formation is never random and follows certain defined rules called twin laws. Many types of twin laws are given their own unique names and some are well known, such as the Spinel Law or the Albite Law. The twin laws are crystallographic in nature and are caused by flaws in the crystal structure that occur during growth or during changes in phases such as from a high temperature phase to a low temperature Witherite phase. One example of how twins form is explained by looking at how (trilling) crystals grow. Most crystals grow by adding layers of atoms, one layer at a time (in a simplistic model). If the first layer is called A and the next layer which is in a different position is called B and the next C followed by another A and so forth, then a structure will be built like so: ABCABCABCABC . . . Many minerals form with such a stacking sequence. But, if an error occurs during growth a twin can be formed. If the next layer of atoms becomes misplaced and assumes the wrong Staurolite position, then the following sequence will form: (penetration twin)

http://mineral.galleries.com/minerals/twins.htm (1 of 5) [8/2/2001 2:52:10 PM] Mineral Gallery - THE TWINNED MINERALS ABCABCABCACBACBACBA Can you see the flaw? The C layer next to the middle A layer is wrong because there should be a B layer next. The rest of the sequence is then repeated as if nothing happened and the crystal grows outward in both directions until finished growing. Directly through the middle A layer, a mirror plane is produced and the right side of the crystal will be a mirror image of the left side just as a left hand is the mirror image of the right Quartz hand. The mirror is easier to see if the A is replaced by a vertical line | (Japan Law Twin) which represents a mirror plane as in: ABCABCABC | CBACBACBA Not all twins are formed this way, but it gives a good idea of how a twin is possible. Twins are recognized by penetration angles or notches in the crystal, mirror planes that do not normally occur on a specific mineral and crystallographic techniques not normally available to the average Muscovite collector. Twinning often has a dramatic effect on the outward (Star Twins) symmetry of the mineral either by raising or lowering the symmetry. Twinning can make an orthorhombic mineral appear hexagonal or make a trigonal mineral appear monoclinic. There are two general types of twin styles; contact and penetration. Contact twins have a composition plane (the twin plane) that forms at the boundary between the two twins. The composition plane is a mirror plane where the two twins can look like reflected images of each other Calcite (like a Siamese twin). The angle between the twins is critical and in (Butterfly Twin) some cases diagnostic. If the angle is 180 degrees then the crystals grow away from each other in opposite directions. If the angle is less than 180 degrees then the twin will have a noticeable bend. These twins form dove-tail, fish-tail and chevron shaped twins. Many twins form penetration twins which look like two crystals that grew into and out of each other. These twins have portions of their respective twins protruding out of each other on different sides. At times it may look as if half the crystal was twisted in the wrong direction or Herderite that whoever made the crystal didn't know how it was supposed to fit (Fishtail Twin) together. The effect is really interesting on well formed twins. These twins can form crosses, 3-D star shapes and complex structures. In some minerals, these two types can be repeated again and again; two, three or nearly an infinite number of times. There are two types of repeat twinning; cyclic and lamellar. Lamellar, which is also called polysynthetic twinning, forms from contact twins repeating continuously one twin after another, even on the microscopic level. Eventually a crystal composed of stacked twin layers is the result. The Feldspar

http://mineral.galleries.com/minerals/twins.htm (2 of 5) [8/2/2001 2:52:10 PM] Mineral Gallery - THE TWINNED MINERALS Diamond Group minerals are the masters of this type of twinning which for the (Penetration Twin) feldspars is know as the Albite Law. If a composition twin has an angle of 30, 45, 60 or 90 degrees and it repeats 3, 4, 6 or so times . . . then it could form a complete circle or cyclic twin. Some classic twins form cyclic twins called "trillings"; where the mineral is composed of three twin components. Other cyclic twins can have 4, 6 or even 8 components, but trillings are the most common. Orthoclase (Penetration Twin) Twinning is actually rather common in the mineral kingdom, however perfectly formed twins are not. Minerals that commonly grow well OTHER formed twins are known to nearly every mineral collector. Twin collecting can be a very enjoyable hobby and most collectors own one or PROPERTIES: more. Even collectors of specific types of minerals must have their respective twins in order to have a "complete" collection. The twinning ● Color phenomena is well studied in the science of mineralogy. The study of ● Luster twins is also important in crystallography, metallurgy, chemistry and ● Diaphaneity biology. ● Crystal Systems Minerals that can form interesting twins along with their typical twinning style: ● Technical Crystal Habits Among the Elements: ● Descriptive Crystal Habits ❍ Diamond (Spinel Law and penetration twins) ● Twinning Among the Sulfides: ● Cleavage ❍ Arsenopyrite (cross-shaped twins) ● Fracture ❍ Bournonite ("Cog Wheel" twins) ● Hardness ❍ Chalcocite (pseudohexagonal cyclic twins) ● Specific Gravity ❍ Chalcopyrite (penetration twins) ● Streak ❍ Cinnabar (pentration twins) ● Fluorescence ❍ Dyscrasite (pentration twins) ● Phosphorescence ❍ Enargite (star shaped cyclic twins) ● Triboluminescence ❍ Galena (Spinel Law twins) ● Thermoluminescence ❍ Loellingite (penetration twins) ● Index of Refraction ❍ Marcasite (polysynthetic twining and ● Birefringence "Cockscomb" twins) ● Double Refraction ❍ Pyrite ("Iron Cross" twins) ● Dispersion ❍ Sphalerite (complex; involving penetration and ● Pleochroism contact twinning)

http://mineral.galleries.com/minerals/twins.htm (3 of 5) [8/2/2001 2:52:10 PM] Mineral Gallery - THE TWINNED MINERALS ● Asterism ❍ Stibnite (bent angles on elongated crystals) ● Chatoyancy ❍ Tetrahedrite (penetration twins) ● Parting ❍ Wurtzite (fourling twins) ● Striations ● radioactivity Among the Halides: ● Magnetism ❍ Boleite (pseudo-cubic twins) ● Odor ❍ Fluorite (classic penetration twins) ● Feel Among the Oxides: ● Taste ❍ Cassiterite (classic trillings) ● Solubility ❍ Chrysoberyl (hexagonal trillings) ● Electrical properties ❍ Rutile (classic eightlings and sixlings, "sagenite" ● Reaction to acids lattice twinning and "elbow" twins) ● Thermal properties ❍ The Spinel Group minerals (Spinel Law twins) ● Associated Minerals ● Notable Localities Among the Carbonates: ● Phantoms ❍ Aragonite (pseudohexagonal trillings) ● Inclusions ❍ Calcite (four different contact twins) ● Pseudomorphs ❍ Cerussite (pseudohexagonal trillings and chevron ● Meteoritic Minerals twins; the very best reticulated twin structures) ❍ Leadhillite (pseudohexagonal trillings and Artini Law twins) ❍ Witherite (pseudohexagonal pyramidal trillings) Among the Sulfates: ❍ Gypsum (fishtail and dove-tail twins) ❍ Spangolite ("hatchet" twins)

Among the Phosphates: ❍ Amblygonite (flattened elongated twins) ❍ Herderite (fishtail twins) ❍ Monazite (penetration twins)

Among the Silicates: ❍ Chabazite (simple and complex penetration twins) ❍ Epididymite (six sided tabular trillings and fish-tail twins)

http://mineral.galleries.com/minerals/twins.htm (4 of 5) [8/2/2001 2:52:10 PM] Mineral Gallery - THE TWINNED MINERALS ❍ Eudidymite (tabular star shaped twins) ❍ All of The Feldspar Group of Minerals especially: ■ Albite (Manebach, Carlsbad, Baveno and of course Albite Law lamellar twins) ■ Andesine (Manebach, Carlsbad and Albite Law lamellar twins) ■ Labradorite (Albite Law lamellar twins) ■ Microcline (Manebach, Carlsbad and Albite Law lamellar twins) ■ Oligoclase (Manebach, Carlsbad and Albite Law lamellar twins) ■ Orthoclase (Manebach, Carlsbad and Albite Law lamellar twins) ■ Sanidine (Manebach, Carlsbad and Albite Law lamellar twins) ❍ Harmotome (Stempel, Perier and Marburg Law twins forming complex cross-like penetration twins) ❍ Muscovite ("star" twins) ❍ Neptunite (penetration twins) ❍ Phenakite (penetration twins) ❍ Phillipsite (Harmotome-like twins) ❍ Quartz (Japan Law, Dauphine Law, Brazil Law and others) ❍ Sphene/Titanite (contact twins) ❍ Staurolite (cross-shaped twins gave it its name) ❍ Tridymite (six rayed trillings)

THE MINERAL REALGAR

● Chemistry: AsS, Arsenic Sulfide ● Class: Sulfides and Sulfosalts ● Uses: A major ore of arsenic, formerly used for pigments, firework coloring agent and as mineral specimens. ● Specimens Realgar is an oddball among the sulfides. It is one of only a few sulfides that are not metallic or opaque or blandly colored. Its structure is analogous to that of sulfur and resembles sulfur in most respects except for color (the name "ruby sulfur" has been applied to realgar). Sulfur has a structure composed of 8 sulfur atoms linked in a ring. Realgar's structure alternates between sulfur atoms and arsenic atoms producing rings of As4S4. The arsenic atoms affect the structure altering it from sulfur's orthorhombic symmetry to realgar's monoclinic symmetry. Realgar occurs in hydrothermal veins with valuable metal sulfide ores and its bright red color can be an aid to prospectors. It also can be found in hot spring deposits and as a volcanic sublimate product (crystallizing from vapors). Realgar gets its name from the Arabic words for "powder of the mine" (rahj al ghar). Realgar is famous for some wonderfully beautiful specimens. Some specimens can have a deep ruby red color with an amazing clarity and a high luster. The color of realgar is truly something to appreciate and cherish. But realgar's beauty is sometimes fleeting. It is an unstable mineral and will alter to a different mineral, pararealgar and eventually to a powder. This process takes time and is accelerated by exposure to light. Specimens should be stored in dark, enclosed containers, and only exposed to light for the brief enjoyment of its owner and friends. This sounds extreme, but wonderfully beautiful realgar specimens are worth preserving for as long as possible. If you are wondering how quickly the deterioration occurs, the answer is immediately, but fortunately very slowly. Ancient Chinese carvings of realgar are still in existence, but badly affected by the deterioration. The deterioration of realgar was thought to produce the closely related yellow orpiment, but this was recently proven to be false and the deterioration product is in fact yellow-orange pararealgar. In old paintings and manuscripts, realgar was a common pigment for paints and dyes. Many of these paintings now have a yellow or orange hue where once the color must have been an original red. PHYSICAL CHARACTERISTICS:

● Color is orange to red. ● Luster is resinous, adamantine to sub-metallic. ● Transparency: Crystals are translucent to transparent.

http://mineral.galleries.com/minerals/sulfides/realgar/realgar.htm (1 of 2) [8/2/2001 2:52:12 PM] REALGAR (Arsenic Sulfide) ● Crystal System: Monoclinic; 2/m. ● Crystal Habits: include prismatic striated crystals with a rounded diamond-like cross-section. They are terminated by a wedge-like dome. Also found as grains, crusts and earthy masses. ● Cleavage is good in one direction. ● Fracture is subconchoidal. ● Hardness is 1.5 - 2 ● Specific Gravity is 3.5 - 3.6 ● Streak is orange to orange-yellow. ● Other Characteristics: Realgar is unstable in light; specimens should be stored in complete darkness, rarely some specimens fluoresce under UV light and crystals are pleochroic between dark red and orange red. ● Associated Minerals almost always include orpiment, also calcite, stibnite and other metal sulfide ores. ● Notable Occurrences include most importantly Hunan Province, China; but also Switzerland; Japan; Macedonia; Mercur, Utah, USA; Romania and many other localities. ● Best Field Indicators are of course color as well as crystal habit, association with orpiment, softness and luster.

THE MINERAL PYRITE

● Chemistry: FeS2, Iron Sulfide ● Class: Sulfides ● Group: Pyrite ● Uses: A very minor ore of sulfur for sulfuric acid, used in jewelry under the trade name "marcasite" and as mineral specimens. ● Specimens Pyrite is the classic "Fool's Gold". There are other shiny brassy yellow minerals, but pyrite is by far the most common and the most often mistaken for gold. Whether it is the golden look or something else, pyrite is a favorite among rock collectors. It can have a beautiful luster and interesting crystals. It is so common in the earth's crust that it is found in almost every possible environment, hence it has a vast number of forms and varieties. Bravoite is the name given to a nickel-rich iron sulfide. It is closely related to pyrite but contains up to 20% nickel. Some mineral books treat it as a variety of pyrite.

Pyrite is a polymorph of marcasite, which means that it has the same chemistry, FeS2, as marcasite; but a different structure and therefore different symmetry and crystal shapes. Pyrite is difficult to distinguish from marcasite when a lack of clear indicators exists. Pyrite's structure is analogous to galena's structure with a formula of PbS. Galena though has a higher symmetry. The difference between the two structures is that the single sulfur of galena is replaced by a pair of sulfurs in pyrite. The sulfur pair are covalently bonded together in essentially an elemental bond. This pair disrupts the four fold symmetry that a single atom of sulfur would have preserved and thus gives pyrite a lower symmetry than galena. Although pyrite is common and contains a high percentage of iron, it has never been used as a significant source of iron. Iron oxides such as hematite and magnetite, are the primary iron ores. Pyrite is not as ecomonical as these ores possibly due to their tendency to form larger concentrations of more easily mined material. Pyrite would be a potential source of iron if these ores should become scarce. Pyrite has been mined for its sulfur content though. During WWII, sulfur was in demand as a strategic chemical and North American native sulfur mines were drying up. A sulfide deposit near Ducktown Tenn. was found to be able to mine pyrite and other sulfides such as pyrrhotite and pentlandite and produce the needed sulfur as well as iron and other metals. The sulfur was used in the production of sulfuric acid, an important chemical for industrial purposes. Now most sulfur production comes from H2S gas recovered from natural gas wells.

http://mineral.galleries.com/minerals/sulfides/pyrite/pyrite.htm (1 of 2) [8/2/2001 2:52:13 PM] PYRITE (Iron Sulfide) PHYSICAL CHARACTERISTICS:

● Color is brassy yellow. ● Luster is metallic. ● Transparency: Crystals are opaque. ● Crystal System is isometric; bar 3 2/m ● Crystal Habits include the cube, octahedron and pyritohedron (a dodecahedron with pentagonal faces) and crystals with combinations of these forms. Good interpenetration twins called iron crosses are rare. Found commonly in nodules. A flattened nodular variety called "Pyrite Suns" or "Pyrite Dollars" is popular in rock shops. Also massive, reniform and replaces other minerals and fossils forming pseudomorphs or copies. ● Cleavage is very indistinct. ● Fracture is conchoidal. ● Hardness is 6 - 6.5 ● Specific Gravity is approximately 5.1+ (heavier than average for metallic minerals) ● Streak is greenish black. ● Other Characteristics: Brittle, striations on cubic faces caused by crossing of pyritohedron with cube. (note - striations on cube faces also demonstrate pyrite's lower symmetry). Pyrite unlike gold is not malleable. ● Associated Minerals are quartz, calcite, gold, sphalerite, galena, fluorite and many other minerals. Pyrite is so common it may be quicker to name the unassociated minerals. ● Notable Occurrences include Illinois and Missouri, USA; Peru; Germany; Russia; Spain; and South Africa among many others. ● Best Field Indicators are crystal habit, hardness, streak, luster and brittleness.

DOLOMITE

● Chemistry: CaMg(CO3)2, Calcium Magnesium Carbonate ● Class: Carbonates ● Group: Dolomite ● Uses: in some cements, as a source of magnesium and as mineral specimens. ● Specimens Dolomite, which is named for the French mineralogist Deodat de Dolomieu, is a common sedimentary rock-forming mineral that can be found in massive beds several hundred feet thick. They are found all over the world and are quite common in sedimentary rock sequences. These rocks are called appropriately enough dolomite or dolomitic limestone. Disputes have arisen as to how these dolomite beds formed and the debate has been called the "Dolomite Problem". Dolomite at present time, does not form on the surface of the earth; yet massive layers of dolomite can be found in ancient rocks. That is quite a problem for sedimentologists who see sandstones, shales and limestones formed today almost before their eyes. Why no dolomite? Well there are no good simple answers, but it appears that dolomite rock is one of the few sedimentary rocks that undergoes a significant mineralogical change after it is deposited. They are originally deposited as calcite/aragonite rich limestones, but during a process call diagenesis the calcite and/or aragonite is altered to dolomite. The process is not metamorphism, but something just short of that. Magnesium rich ground waters that have a significant amount of salinity are probably crucial and warm, tropical near ocean environments are probably the best source of dolomite formation. Dolomite in addition to the sedimentary beds is also found in metamorphic marbles, hydrothermal veins and replacement deposits. Except in its pink, curved crystal habit dolomite is hard to distinguish from its second cousin, calcite. But calcite is far more common and effervesces easily when acid is applied to it. But this is not the case with dolomite which only weakly bubbles with acid and only when the acid is warm or the dolomite is powdered. Dolomite is also slightly harder, denser and never forms scalenohedrons (calcite's most typical habit).

Dolomite differs from calcite, CaCO3, in the addition of magnesium ions to make the formula, CaMg(CO3)2. The magnesium ions are not the same size as calcium and the two ions seem incompatible in the same layer. In calcite the structure is composed of alternating layers of carbonate ions, CO3, and calcium ions. In dolomite, the magnesiums occupy one layer by themselves followed by a carbonate layer which is followed by an exclusively calcite layer and so forth. Why the alternating layers? It is probably the significant size difference between calcium and magnesium and it is more stable to group the differing sized ions into same sized layers. Other carbonate minerals that have this alternating layered structure belong to the Dolomite Group. Dolomite is the principle member of the Dolomite Group of

http://mineral.galleries.com/minerals/carbonat/dolomite/dolomite.htm (1 of 2) [8/2/2001 2:52:14 PM] DOLOMITE (Calcium Magnesium Carbonate) minerals which includes ankerite, the only other somewhat common member. Dolomite forms rhombohedrons as its typical crystal habit. But for some reason, possibly twinning, some crystals curve into saddle-shaped crystals. These crystals represent a unique crystal habit that is well known as classical dolomite. Not all crystals of dolomite are curved and some impressive specimens show well formed, sharp rhombohedrons. The luster of dolomite is unique as well and is probably the best illustration of a pearly luster. The pearl-like effect is best seen on the curved crystals as a sheen of light can sweep across the curved surface. Dolomite can be several different colors, but colorless and white are very common. However it is dolomite's pink color that sets another unique characteristic for dolomite. Crystals of dolomite are well known for their typical beautiful pink color, pearly luster and unusual crystal habit and it is these clusters that make very attractive specimens. PHYSICAL CHARACTERISTICS:

● Color is often pink or pinkish and can be colorless, white, yellow, gray or even brown or black when iron is present in the crystal. ● Luster is pearly to vitreous to dull. ● Transparency crystals are transparent to translucent. ● Crystal System is trigonal; bar 3 ● Crystal Habits include saddle shaped rhombohedral twins and simple rhombs some with slightly curved faces, also prismatic, massive, granular and rock forming. Never found in scalenohedrons. ● Cleavage is perfect in three directions forming rhombohedrons. ● Fracture is conchoidal. ● Hardness is 3.5-4 ● Specific Gravity is 2.86 (average) ● Streak is white. ● Other Characteristics: Unlike calcite, effervesces weakly with warm acid or when first powdered with cold HCl. ● Associated Minerals: include calcite, sulfide ore minerals, fluorite, barite, quartz and occasionally with gold. ● Notable Occurrences include many localities throughout the world, but well known from sites in Midwestern quarries of the USA; Ontario, Canada; Switzerland; Pamplona, Spain and in Mexico. ● Best Field Indicators are typical pink color, crystal habit, hardness, slow reaction to acid, density and luster.

THE MINERAL QUARTZ

● Chemistry: SiO2 , Silicon dioxide ● Class: Silicates ● Subclass: Tectosilicates ● Group: Quartz ● Uses: silica for glass, electrical components, optical lenses, abrasives, gemstones, ornamental stone, building stone, etc. ● The Physical Properties of Quartz. ● Specimens Additional variety specimens include: ❍ Amethyst ❍ Citrine ❍ Rock Crystal ❍ Rose Quartz ❍ Smoky Quartz Quartz is the most common mineral on the face of the Earth. It is found in nearly every geological environment and is at least a component of almost every rock type. It frequently is the primary mineral, >98%. It is also the most varied in terms of varieties, colors and forms. This variety comes about because of the abundance and widespread distribution of quartz. A collector could easily have hundreds of quartz specimens and not have two that are the same due to the many broad catagories. The specimens could be separated by answers to the following questions: color?, shade?, pyramidal?, prismatic?, druzy?, twinned?, sceptered?, tapered?, phantomed?, inclusions?, coated?, microcrystalline?, stalactitic?, concretionary?, geoidal?, tappered?, banded?, etc. Multiple combinations of these could produce hundreds of unique possibilities. Some macrocrystalline (large crystal) varieties are well known and popular as ornamental stone and as gemstones. ● Amethyst is the purple gemstone variety. ● Citrine is a yellow to orange gemstone variety that is rare in nature but is often created by heating Amethyst. ● Milky Quartz is the cloudy white variety.

http://mineral.galleries.com/minerals/silicate/quartz/quartz.htm (1 of 3) [8/2/2001 2:52:15 PM] QUARTZ (Silicon Dioxide) ● Rock crystal is the clear variety that is also used as a gemstone. ● Rose quartz is a pink to reddish pink variety. ● Smoky quartz is the brown to gray variety. Cryptocrystalline (crystals too small to be seen even by a microscope) varieties are also used as semi-precious stones and for ornamental purposes. These varieties are divided more by character than by color. Chalcedony or agate is divided into innumeral types that have been named for locally common varieties. Some of the more beautiful types have retained their names on a world-wide basis while other names have faded into obscurity. Some of the more common of these types are chrysoprase (a pure green agate), sard (a yellow to brown agate), sardonyx (banded sard), onyx (black and white agate), carnelian (a yellow to orange agate), flint (a colorful and microscopically fibrous form), jasper (a colorful impure agate) and bloodstone (a green with red speckled agate).

Quartz is not the only mineral composed of SiO2. There are no less than eight other known structures that are composed of SiO2. These other substances and quartz are polymorphs of silicon dioxide and belong to an informal group called the Quartz Group or Silica Group. All members of this group, except quartz, are uncommon to extemely rare on the surface of the earth and are stable only under high temperatures and high pressures or both. These minerals have their own unique structures although they share the same chemistry, hence the term polymorph, which means many forms. Quartz has a unique structure. Actually, there is another mineral that shares quartz's structure, and it is not even a silicate. It is a rare phosphate named berlinite, AlPO4, that is isostructural with quartz. The structure of quartz involves corkscrewing (helix) chains of silicon tetrahedrons. The corkscrew takes four tetrahedrons in order to repeat itself, or three turns. Each tetrahedron is essentially rotated 120 degrees. The chains are aligned along the c axis of the crystal and interconnected to two other chains at each tetrahedron making quartz a true tectosilicate. This structure is not like the structure of the chain silicates or inosilicates whose silicate tetrahedronal chains are not directly connected to each other. The structure of quartz helps explain many of its physical attributes. For one, the helix makes three turns and this helps produce the trigonal symmetry of quartz. Likewise a helix or corkscrew lacks mirror planes of symmetry as does quartz. The corkscrew structure would also disrupt any cleavage which requires a plane of weakness not found in quartz and breakage would result in the curved fracture, conchoidal, that is found in quartz. Quartz can also have left and right handed crystals just as a corkscrew can screw in a left handed way or in a right handed way. There are even some very difficult to identify crystals of quartz that are twinned with alternating one sixths of the crystal being right handed and then left handed. Quartz is a fun mineral to collect. Its abundance on the Earth's surface is incredible and produces some wonderful varieties that don't even look like the same mineral. A collector must always be up on the many varieties of quartz and it sometimes embarrasses a collector to have collected too many specimens of such a common mineral. But nearly all collectors concede that you can never really have enough quartz specimens.

http://mineral.galleries.com/minerals/silicate/quartz/quartz.htm (2 of 3) [8/2/2001 2:52:15 PM] QUARTZ (Silicon Dioxide) PHYSICAL CHARACTERISTICS:

● Color is as variable as the spectrum, but clear quartz is by far the most common color followed by white or cloudy (milky quartz). Purple (Amethyst), pink (Rose Quartz), gray or brown to black (Smoky Quartz) are also common. Cryptocrystalline varieties can be multicolored. ● Luster is glassy to vitreous as crystals, while cryptocrystalline forms are usually waxy to dull but can be vitreous. ● Transparency crystals are transparent to translucent, cryptocrystalline forms can be transparent, translucent or opaque. ● Crystal System is trigonal; 32 ● Crystal Habits are again widely variable but the most common habit is hexagonal prisms terminated with a six sided pyramid (actually two rhombohedrons). Three of the six sides of the pyramid may dominate causing the pyramid to be or look three sided. Left and right handed crystals are possible and identifiable only if minor trigonal pyramidal faces are present. Druse forms (crystal lined rock with just the pyramids showing) are also common. Massive forms can be just about any type but common forms include botryoidal, globular, stalactitic, crusts of agate such as lining the interior of a geode and many many more. ● Cleavage is not present. ● Fracture is conchoidal. ● Hardness is 7, less in cryptocrystalline forms. ● Specific Gravity is 2.65 or less if cryptocrystalline. (average) ● Streak is white. ● Other Characteristics: striations on prism faces run perpendicular to C axis, piezoelectric (see tourmaline) and index of refraction is 1.55. ● Associated Minerals are numerous and varied but here are some of the more classic associations of quartz (although any list of associated minerals of quartz is only a partial list): amazonite a variety of microcline, tourmalines especially elbaite, wolframite, pyrite, rutile, zeolites, fluorite, calcite, gold, muscovite, topaz, beryl, hematite and spodumene. ● Best Field Indicators are first the fact that it is very common (always assume transparent clear crystals may be quartz), crystal habit, hardness, striations, lack of cleavage and good conchoidal fracture. ● Notable Occurances of amethyst are Brazil, Uraguay, Mexico, Russia, Thunder Bay area of Canada, and some locallities in the USA. For Smoky Quartz; Brazil, Colorado, Scotland, Swiss Alps among many others. Rose Quartz is also wide spread but large quantities come from brazil as do the only large find of Rose Quartz prisms. Natural citrine is found with many amethyst deposits but in very rare quantities. Fine examples of Rock crystal come from Brazil (again), Arkansas, many locallities in Africa, etc. Fine Agates are found in, of course, Brazil, Lake Superior region, Montana, Mexico and Germany.

THE MINERAL STIBNITE

● Chemistry: Sb2S3, Antimony Sulfide ● Class: Sulfides ● Uses: An ore of antimony and as mineral specimens. ● Specimens Stibnite is a classic mineral species with fine crystal clusters and long curved crystals being the pride of many collectors. The slender curved metallic blades of stibnite can resemble arabian swords. The curving of the long bladed crystals is due to twinning where one twin plane bends the crystal one direction and another twin plane bends it in the other direction. This can occur numerous times down the length of one crystal. Stibnite's crystal clusters are admired for their distinctive look with dozens of accicular or bladed crystals jutting out in many divergent directions. PHYSICAL CHARACTERISTICS:

● Color is steel gray to silver. ● Luster is metallic. ● Transparency crystals are opaque. ● Crystal System is orthorhombic; 2/m 2/m 2/m ● Crystal Habits include bladed or acicular crystals often bent or curved due to twinning, also granular and massive. ● Cleavage is perfect in the lengthwise direction. ● Fracture is irregular. ● Hardness is 2 ● Specific Gravity is approximately 4.6+ (average for metallic minerals) ● Streak is a dark gray. ● Other Characteristics: striated lengthwise sometimes deeply, luster brighter on cleavage surfaces and crystals slightly flexible. ● Associated Minerals include quartz, calcite, gold, arsenopyrite and other sulfides. ● Notable Occurrences include Hunan province, China; Japan; Germany; Brazil; Peru and South Africa. ● Best Field Indicators are crystal habit, softness and flexibility.

NATIVE MERCURY

● Chemistry: Hg, Elemental Mercury ● Class: Elements ● Group: Gold ● Uses: Minor ore of mercury, electrical switches, thermometers ● Specimens Mercury is unique, as it is the only metal that is liquid at room temperature, having a melting point of -40 C, and a boiling point of 357 C. This silvery liquid metal is very dense, yet has a high surface tension that causes is to form tiny little perfect spheres in the pores of the rocks it is found in. Many mineralogical characteristics simply do not apply to a liquid: there is no "hardness", since it cannot be scratched (nor can it scratch); there is no crystal structure, no fracture, no cleavage, no streak; all of course, at room temperatures. When frozen, mercury forms crystals in the rhombohedral system at low pressure, and in the tetragonal system at high pressure. PHYSICAL CHARACTERISTICS:

● Color is bright silvery metalic. ● Luster is metallic. ● Transparency is opaque. ● Crystal System does not apply ● Crystal Habits spherical droplets, or pools of mercury liquid. ● Cleavage does not apply ● Fracture does not apply ● Streak does not apply ● Hardness does not apply ● Specific Gravity is 13.5+ (very dense) ● Associated Minerals are cinnabar, calomel, and other secondary mercury minerals. ● Other Characteristics: Mercury is a liquid! It also expans at a constant rate with a rise in temperature. ● Notable Occurrences include Almaden, Spain; Idrija, former Yugoslavia; Italy; California, Oregon, Texas, and Arkansas, USA. ● Best Field Indicators its a liquid!

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