Most of the time when we appreciate minerals, we are amazed by their magnificent colors and regular crystal forms, but in fact many minerals also have their own unique smell.

Most of the time when we appreciate minerals, we are amazed by their magnificent colors and regular crystal forms, but in fact many minerals also have their own unique smell. In fact, I guess the person who is most familiar with mineral smells is not a mineralogist, but a wine taster.

For wine tasting, describing the aroma of wine is the most basic one. In addition to the common floral, fruity and plant aromas, the aroma of wine also has a very special aroma - mineral aroma. This sounds like a very ethereal and difficult-to-understand aroma, but in fact many people believe that the mineral aroma in wine is related to the "terroir" of the production area, that is, the local soil and geological environment. Although this statement is still very controversial, and some people even completely deny this statement, it has to be said that this allows us to better understand the aroma of minerals.

The beautiful scenery of the wine estate

In the eyes of many tasters, different strata and lithology will give different mineral aromas to the wine. For example, the slate from the Mosel region in Germany will bring a sharp mineral flavor to the local wine Riesling, while the red wine from Spain's Rioja (Rioja), especially Grenache (Garnacha) The earthy mineral aroma comes from local schist. There is also a very unique and aggressive smell in the mineral aroma - the smell of flint or gunfire. The obvious flint smell in the wine Chablis is said to be related to the local chalk rock that is rich in ancient small shellfish fossils. - It is related to a kind of loose earthy limestone, and the gunfire smell of Sauvignon Blanc produced in Pouilly Fumé on the Loire River in France is considered to be the local flint-containing soil and Sauvignon Blanc grapes. The result of the acidic mix.

Chablis Village Grape Plantation Estate

Of course, the cause of this mineral aroma is still highly controversial, and many people even think that it has nothing to do with soil minerals or local terroir. However, in addition to this ethereal smell, many minerals have real smells, but they are hidden so deeply that we often cannot smell them.

Next, let’s get to know the smell of these mysterious minerals!

Arsenic pyrite

01

Arsenic pyrite, also known as arsenopyrite, has a chemical formula of FeAsS. Arsenopyrite belongs to the monoclinic crystal system, and the crystals are often columnar, sometimes cross-shaped, and sometimes plate-shaped. The color is tin white with metallic luster.

The crystal form of arsenopyrite

The smell of arsenopyrite comes from the arsenic element in its chemical composition. Under normal temperature and pressure, arsenopyrite has no special smell. But if you hit it hard with a hammer, it will emit the distinctive garlic smell of arsenic. Due to the high arsenic content in arsenopyrite, it is also the main mineral raw material for producing arsenic and various arsenic compounds. Arsenic, a very famous poison in ancient times, was extracted from arsenopyrite. Therefore, arsenopyrite was also called "arsenic " in the past.

Arsenopyrite is an arsenic mineral widely distributed in metal deposits. It is often formed in hydrothermal deposits, but most of it is concentrated in high- and medium-temperature arsenopyrite quartz veins and tungsten and tin ores.

scorodite

02

The beautiful scorodite

arsenopyrite has a "smelly" relative, that is scorodite. I don’t know who this mineral offended, but its name sounds extremely smelly. But in fact, scorodite is a very beautiful mineral and can even be appreciated as a gemstone.

Although the name is ugly, it is really good-looking.

Scorodite is often distributed in the oxidation zone of arsenopyrite-rich mineral deposits. In fact, scorodite is a weathering product of arsenopyrite and rhombic arsenite, and its chemical formula is Fe (AsO₄)2H₂O. Then it is not difficult for us to guess that the smell of scorodite, like arsenopyrite, comes from the arsenic element in it. In addition to the fact that scorodite, like arsenopyrite, emits the smell of garlic after being hit hard, it has another way to release its smell.When scorodite is heated to 450-800°C, it will also emit a strong garlic smell. This is due to the smell produced by the decomposition of scorodite to form FeAs at high temperatures.

Scorodite crystal form

Of course, people cannot be judged by their appearance. The colors of scorodite are rich and colorful, and gem-grade scorodite is mostly blue and purple, with glass luster or grease luster. Scorodite belongs to the orthorhombic crystal system . The crystal is usually bipyramidal or columnar, often in the form of granular aggregates. In addition to its beautiful appearance, scorodite is also one of the main minerals for refining arsenic. When the nickel and cobalt in scorodite reach a certain grade, it is also an extremely important mineral resource. If

minerals contain arsenic, they will basically have a unique garlic smell; while sulfur will cause the unique gunfire smell, or firecracker smell, mentioned above. Of course, it is possible for both to appear simultaneously in the same mineral. For example, realgar (As₄S₄) and orpiment (As₂S₃), both have a specific slight odor, but when realgar is burned, it will produce white smoke and emit the unique garlic smell of arsenic.

Realgar

Orpiment

The color of orpiment's streaks is bright yellow

However, in addition to the special gunfire smell, sulfur will also have a more peculiar odor after combining with hydrogen. I don’t know if you still remember the very famous smelly gas in high school - hydrogen sulfide (H₂S). Hydrogen sulfide gas has a very iconic smell of rotten eggs. However, it is difficult to imagine that this gas can actually appear in minerals. This mineral is different from scorodite. It has a seemingly harmless name: heliolite.

Heliolite

03

Heliolite (Mn₈[BeSiO₄]₆S₂), which belongs to the equiaxed crystal system and is a beryllium silicate series. There must be many people who think that its name is very similar to garnet , and there must be a certain connection. The guess is very reasonable. Under the microscope, heliolite is indeed very similar to garnet. However, if heliolite is thrown into hydrochloric acid, it will release the unique smell of hydrogen sulfide gas, which is not characteristic of garnet.

Heliolite

Heliolite garnet, which is very similar to garnet, often appears in granite pegmatite and greitz , and is symbiotic with

beryl , topaz, wolframite and other minerals. Sometimes it also appears in contact with metamorphic zones, skarn and hydrothermal veins, and is symbiotic with fluorite, magnetite and sphalerite. Sun garnet belongs to the sun garnet family. In addition to itself, there are also mineral varieties such as beryllium garnet and zinc sun garnet. The only difference between them is the incomplete isomorphous substitution between manganese, iron and zinc, but in Among this group, only heliolites uniquely emit the smell of rotten eggs. However, since the minerals of the heliolite group are all beryllium silicate minerals, they are all important mineral raw materials for beryllium.

!

Warm reminder

These unpleasant smells have a certain degree of toxicity. Friends, please don’t smell them casually~

I have seen so many minerals with strange smells, but there are also minerals with fragrant smells. Its name is also very straightforward, it is called " Xiangshi ", and in some places it is also called " Jinxiangyu ". It is actually a kind of serpentine mineral with a very unique aroma. It is a jade with a natural creamy chocolate aroma. Just hearing the description makes you very excited.

Serpentine Diopside Marble

Unfortunately, the source of the aroma of fragrant stone is not very clear yet. Fragrant stone was discovered somewhere at the junction of Sichuan and Shaanxi in my country in 2004. However, although its traces were only recently discovered, it has been recorded in ancient Chinese books. Chen Zhilong described the jade articles carved from fragrant jade in the book "Ge Zhi Jing Yuan" as follows: "Su Zong gave Li Fuguo two fragrant jade to ward off evil spirits. Each one is one foot and five inches high. They are ingenious and unparalleled in the world. The fragrance of their jade can be smelled. After walking hundreds of steps, even though it was locked in a golden letter and stone cabinet, it could not hide its fragrance."

Brown fragrant stone

Many scholars are very curious about the source of the natural creamy chocolate flavor of fragrant stone, and have conducted a series of mineralogical analyzes on fragrant stone. The fragrant stones used are often collected from the metamorphic rock at the junction of Sichuan and Shaanxi in my country. The distribution is not uniform, and there are small pieces, lumps, strips, etc. Finally, it was determined through infrared spectrum and X-ray data that the fragrant stone is a kind of serpentine. But what is strange is that there are 67 kinds of organic components in the volatile matter of fragrant stone, and it has been identified as containing 18 kinds of organic compounds with fragrance. As a kind of serpentine, fragrant stone is a layered silicate mineral, so it has a curled cylindrical tubular structure. This unique structure determines that fragrant stone has adsorption ability, so it absorbs many organic substances with fragrance. So where does this organic matter come from? Still a big mystery. Some people speculate that it may be that the adsorbed organic matter matures under the unique temperature and pressure environment generated by the geological tectonic movement of , causing the serpentine to produce this unique flavor of cream chocolate.

Dark brown fragrant stone

It is said that a good dish is full of flavor and aroma. In fact, the same is true for many minerals. They all have their own unique taste waiting for us to discover. Sometimes, the unique smell of a mineral is its own symbol, and it is also a good way for us to identify it.

Image source:

Wikipedia , Google

https://www.mindat.org/

References

[1] Xie Yuan. Gemological characteristics of serpentine jade "Jinxiang Jade" from Hanzhong, Shaanxi. China University of Geosciences (Beijing), 2019 .

[2]Chang Lihua, Chen Manyun, Jin Wei. Handbook of Identification of Transparent Mineral Thin Sections[M]. Geological Publishing House, 2006.

[3]Chen Zheng. Microscopic Identification of Opaque Minerals[M]. Geological Publishing House, 1959.

[4] Institute of Geology and Mineral Resources, Chinese Academy of Geological Sciences. Sand Mineral Identification Manual [M]. Geological Press, 1977.

Artist editor: Zhu Wenxiao

Proofreader: Wang Haibo