Stibnite

Authors: Hannah, Sophia J, Sophia T.

Mineral Name: Stibnite

Chemical Composition: Sb2S3

Color: lead-grey with pale blue tint (2).

Streak: lead-grey

Hardness: 2

Cleavage/Fracture: Perfect in 1 direction, meaning that it breaks perfectly parallel (2).

Crystal Form: Stibnite forms in a cluster of angular rods, needles, pillars, etc (9). Each rod is square-like and varies in sizes. These needles can be oriented in all different directions or they can be very uniformly oriented. The crystal system is prominently displayed in the rods. Stibnite’s crystal form is orthorhombic, meaning there are three axes in the crystal that are all unequal in length and are at 90* degrees to each other (9). The samples can also be smoother and more layered looking when not displaying the distinct rods.

Luster: Metallic

Special Features: Stibnite has a low melting point. Due to its low melting point, it fuses under a candle flame. Stibnite is also a little poisonous, so you should always wash your hands after handling and not touch anything else till you do so. (2)

Varieties: There is only one variety of stibnite. This variety is called selenian stibnite, which contains selenium as opposed to sulfur. It is commonly found in China, with few appearances in Poland, and is not frequently found in the U.S. (6).

Mineral Group: Stibnite is part of the sulfide mineral group, meaning it has sulfur in the makeup, along with antimony in this case. It is more specifically considered a simple sulfide, meaning that it contains at least one true metal and the element of sulfur. (9)

Environment: Stibnite is found in hydrothermal deposits. A hydrothermal deposit is an assembly of minerals that can be metallic or valuable. The minerals are deposited through the circulation of hot water in the Earth’s crust through fractures (10). Stibnite is found in veins of quartz and in beds of granite (4). One could see an example of stibnite in quartz veins, in Lake George. Lake George is located in Brunswick, Canada and is part of the geoenvironmental model of “stibnite-quartz” deposits (11). Typically in association to quartz, stibnite is deposited in alkaline waters (4). This is in reference to the pH level in the water. Alkaline waters typically have a 7 or 8 on the pH scale, which refers to a neutral pH level.

Associated Rock types: Stibnite most often will form in granite, limestone, shale, and gneiss (13).

Occurrence in North America: There are significant findings of stibnite in the western region of the United States, including California, Nevada, Idaho, Arkansas, and up north in Alaska. (9)

Economic Uses: Stibnite is 72% Antimony and 28% Sulfur, and it is the antimony that is used economically. For instance, antimony is used in the computer industry. It is currently being used as a semiconductor, and is being tested and revised to be used in other materials for the computer industry (14). Antimony is also used as the metal for printing magazines and newspapers. Finally, it can be alloyed with tin to make cups, plates, and pitchers for decoration (2).

Industrial Uses: Stibnite is mined and smelted to obtain antimony, an important metal. Smelting is a process where a metal is obtained by heating metal-rich rocks beyond the melting point (8). Antimony is a very useful mineral because it expands when it cools and freezes. This can come in handy when fitting into a mold of some sort because it can expand to the maximum capacity of the mold. Antimony can be used for fireworks, foil, sheets, and pipes. It can also be used in rubber, plastics, and paints. (2).

First Notable Identification: Stibnite was innovatively used as a cosmetic by the Egyptians. Powered stibnite and kohl created a black paste that was used as eyeliner and a detailer. This tells us that stibnite was in fact used in ancient times, probably for at least 6 millenia (3). In 1707, stibnite was studied by a chemist named Nicolas Lémery who is known for some of the earliest examinations performed on stibnite (5). However, stibnite did not receive it’s official name until much later into its identification and studies. In 1832, a mineralogist named Francois Sulpice Beudant, named this mineral (6). Beudant is known for naming many other minerals as well (6).

How We Identified It: Stibnite has a different texture than most of the minerals we work with. It looks like a group of crystals formed together, in a radiating starburst or a group of needles. It is very chunky and you can easily see the chunks of mineral in it. Something that also makes it different from the other minerals is that this mineral is slightly poisonous. So, after handling the mineral, your hands need to be washed before touching anything else. It has a lead grey color, with a pale blue tint in it, so that can also set it apart from the other minerals you see.

Don’t Confuse It With:. Stibnite can be confused with both galena and arsenopyrite due to the similarities in color and appearance. Some ways to differentiate between them and stibnite would be their hardness, streak and density. Galena is much denser than stibnite, but they do have a similar hardness as the hardness of galena is 2.5 and stibnite is a 2; in addition, to this the streak is also black in comparison to the gray of the stibnite. Arsenopyrite is both denser and harder than stibnite, it has a hardness of about a 6 and the streak is black in comparison to the gray of the stibnite.



Bibliography:

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  2. Antimony, Minerals Education Coalition, 2020, mineralseducationcoalition.org/minerals-database/antimony/.

  3. Carlin, J.F., and W.C. Butterman. “Mineral Commodity Profiles : Antimony.” Pubs.usgs.gov, U.S. Geological Survey, 2004, pubs.usgs.gov/of/2003/of03-019/of03-019.pdf.

  4. Geology Science. “Stibnite : Physical - Optical Properties, Occurrence, Uses.” Geology Science, 9 July 2019, geologyscience.com/minerals/stibnite/.

  5. “It's Elemental.” It's Elemental - The Element Antimony, education.jlab.org/itselemental/ele051.html.

  6. Jordan, Sarah. “Understanding Stibnite.” The Gemmological Association of Great Britain, gem-a.com/news-publications/news-blogs/gems-from-gem-a/gem/understanding-stibnite-antimony-minerals.

  7. “Selenian Stibnite.” Selenian Stibnite: Mineral Information, Data and Localities., www.mindat.org/min-31625.html.

  8. "Smelting ." Encyclopedia Britannica, www.britannica.com/technology/quenching-materials-processing.

  9. “Stibnite.” Stibnite: Mineral Information, Data and Localities., www.mindat.org/min-3782.html.

  10. “Stibnite: The Mineral Stibnite Information and Pictures.” Stibnite: The Mineral Stibnite

Information and Pictures, m.minerals.net/mineral/stibnite.aspx.

  1. Stibnite from Lake George Antimony Mine (Consolidated Durham Mines; Resources Ltd. Mine; Prince William Mine; Brunswick Mine), Lake George, Prince William Parish, York Co., New Brunswick, Canada, www.mindat.org/locentry-21863.html.

  2. The Editors of Encyclopaedia Britannica. “Hydrothermal Mineral Deposit.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 19 Feb. 2014, www.britannica.com/science/hydrothermal-mineral-deposit.

  3. The Editors of Encyclopaedia Britannica. “Stibnite.” Encyclopædia Britannica, Encyclopædia

Britannica, Inc., 4 Jan. 2019, www.britannica.com/science/stibnite.

  1. University of Texas at Austin. "2D antimony holds promise for post-silicon electronics: New material for manufacturing even smaller computer chips to replace silicon." ScienceDaily. ScienceDaily, 4 November 2019. <www.sciencedaily.com/releases/2019/11/191104190703.htm>.