Mineralogist Answers Gemstone Questions From Twitter | Tech Support | WIRED

WIRED

4 Jan 202417:44

EducationalLearning

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TLDRGabriela Farfan, the curator of gems and minerals at the Smithsonian, addresses various questions about the nature of rocks, minerals, and gemstones in an informative and engaging manner. She explains that rocks are composed of minerals and highlights the composition of granite. Farfan describes the process of turning mineral crystals into gemstones and the differences between precious gems like rubies, emeralds, and sapphires, which are all varieties of corundum with color variations due to trace element impurities. She also introduces Hackmanite, a unique sodalite variety that exhibits tenebrescence, glowing under UV light. The Mohs Hardness Scale is discussed, with diamonds being the hardest and jade being the most difficult to break. Farfan reveals how diamonds are cut using diamond powder and how their purity is graded based on the four Cs: color, clarity, cut, and carat weight. She touches on the topic of synthetic diamonds and their similarities to natural ones, as well as the geological transformation of diamonds into graphite over millions of years. The script also covers the origins of obsidian, the difference between fool's gold (pyrite) and real gold, and the vast number of known mineral species on Earth. Farfan explores the sources of minerals in mobile phones, the allure of the Hope Diamond, and the process of crystal formation. She clarifies the distinction between minerals and organic materials like pearls and the biological processes that form bio-minerals. The video concludes with insights into the jewelry industry, ethical sourcing of gemstones, and the curator's role in discovering and acquiring new gemstones for the Smithsonian.

Takeaways

😊 Rocks are made up of minerals, with granite being a prime example.
🔍 Gemstones are mineral crystals that have been cut and faceted into specific shapes.
💎 Rubies and sapphires are the same mineral, corundum, with different colors designated by the gem industry.
🌈 Emeralds get their green color from chromium impurities, while other colors of corundum are called sapphires.
🔦 Hackmanite, a variety of sodalite, exhibits tenebrescence, glowing under UV light.
🔢 Dwayne Johnson's bones are made of the mineral apatite, with a Mohs hardness of 5.
💍 Diamonds are hardest on the Mohs scale, making them resistant to scratches in jewelry.
💎 Diamonds are cut using other diamonds, with various shapes and cuts available.
💎 The 4Cs (color, clarity, cut, and carat weight) determine a diamond's quality and value.
💎 Synthetic diamonds have the same properties as natural diamonds but are created in laboratories.

Q & A

What is the difference between rocks and minerals?
-Rocks are composed of minerals, which are naturally occurring inorganic substances with a definite chemical composition and crystalline structure. For example, granite is a rock that includes minerals such as quartz, feldspar, and mica.
How are rubies and sapphires related?
-Rubies and sapphires are both varieties of the mineral corundum, composed of aluminum oxide. The primary distinction is color; rubies are red, and sapphires can be any other color.
What causes the different colors in minerals like rubies and emeralds?
-Colors in minerals often result from trace element impurities. For example, rubies are red due to chromium impurities, while emeralds gain their green color from traces of chromium or vanadium.
What is tenebrescence, as seen in hackmanite?
-Tenebrescence is a color change phenomenon observed in certain minerals like hackmanite, where exposure to UV light alters the color of the mineral temporarily.
How do synthetic diamonds compare to natural diamonds?
-Synthetic diamonds have the same chemical and physical properties as natural diamonds, including hardness and optical qualities. They are made in laboratories, mimicking natural geological processes.
What is the Mohs Hardness Scale?
-The Mohs Hardness Scale measures the scratch resistance of various minerals, from talc at 1, being the softest, to diamond at 10, the hardest.
Why are pearls not considered minerals?
-Pearls are organic and formed by living organisms (oysters), which excludes them from being classified as minerals, which must be inorganic in origin.
What are the four Cs used to grade diamonds?
-The four Cs stand for Color, Clarity, Cut, and Carat weight. These factors determine the quality and value of a diamond.
How are gems cut from their natural crystal form?
-Gems are cut from crystals using a lap covered with diamond powder. This process starts with a coarse grit and progresses to finer grits to achieve a polished effect.
What is the significance of the Hope Diamond's alleged curse?
-The Hope Diamond is famed not only for its size and beauty but also for the curse associated with its history of bringing misfortune to its owners. However, it's now considered a cornerstone of the Smithsonian's National Gem collection, symbolizing a blessing rather than a curse.

Outlines

00:00

🌟 Gem and Mineral FAQs: Differences, Gems, and Hardness

Gabriela Farfan, curator at the Smithsonian, answers internet queries on gems and minerals. She explains the composition of rocks and minerals, using granite as an example, and discusses the differences between rubies, sapphires, and emeralds based on impurities that provide color. She introduces unique minerals like Hackmanite, known for its color-changing properties under UV light. Farfan humorously rates Dwayne 'The Rock' Johnson on the Mohs Hardness Scale, explaining the scale's logarithmic nature and the significance of hardness in gemstones, like diamonds, for jewelry.

05:02

💎 Diamond Grading, Synthetic Diamonds, and Mobile Phone Minerals

The grading of diamonds is explained through the 'Four Cs': color, clarity, cut, and carat weight. Farfan touches on synthetic diamonds, noting they share properties with natural diamonds but are created in labs. She also details the origins of minerals used in mobile phones, highlighting the extraction of rare Earth elements from pegmatites. Furthermore, Farfan discusses obsidian's prehistoric uses, the visual comparison between real gold and fool's gold, and the theoretical limits of known minerals, suggesting thousands more could be discovered.

10:04

🔮 Cursed Diamonds, Crystal Formation, and the Nature of Pearls

Farfan shares stories of the Hope Diamond's cursed reputation and its significance in the National Gem collection. She explains how crystals form under specific conditions, using amethyst as an example. The organic origin of pearls is discussed, clarifying why they are not considered minerals. Questions about the definition of 'gem' lead to a discussion about gem potential in minerals like emerald. Farfan also addresses misconceptions about moonstones and opals in jewelry care, emphasizing opals' susceptibility to water damage.

15:05

💰 The Economics of Turquoise Jewelry and the Global Origins of Rubies

The expensive nature of turquoise jewelry is attributed to the rarity of suitable mineral specimens and the comprehensive process from mining to jewelry setting, involving lapidaries and jewelers. Farfan discusses the widespread sources of rubies, with a focus on the prestigious rubies from Burma. She addresses the controversial topic of blood diamonds, explaining the Kimberley Process for verifying diamond origins to prevent conflict diamond trade. Lastly, Farfan reveals how she and her team source gems and minerals for the Smithsonian.

Mindmap

Keywords

💡Minerals

Minerals are naturally occurring, inorganic substances with a specific internal structure and chemical composition. They are the building blocks of rocks. In the video, Gabriela Farfan explains that rocks are made up of minerals, using granite as an example, which contains quartz, feldspar, biotite, and muscovite.

💡Gemstones

Gemstones are mineral crystals that have been cut and faceted by an artist to enhance their beauty and are used in jewelry. They are valued for their beauty, rarity, and durability. The video discusses that a gemstone is a type of mineral that has been shaped and polished to be used in jewelry, with the natural shape of a crystal being maintained.

💡Corundum

Corundum is a mineral consisting of aluminum and oxygen, and it is the same mineral found in both rubies and sapphires. The difference between the two lies in their color; rubies are red due to the gem industry's designation, while sapphires can be any other color. The video explains that corundum is the mineral that makes up rubies and sapphires, highlighting the role of trace element impurities in determining their color.

💡Mohs Hardness Scale

The Mohs Hardness Scale is a qualitative scale used to rank the relative hardness of minerals based on their ability to scratch or be scratched by other minerals. It ranges from 1 (softest, talc) to 10 (hardest, diamond). The video uses the Mohs Hardness Scale to illustrate the difference in hardness between various minerals, emphasizing the importance of hardness in gemstones used in jewelry.

💡Synthetic Diamonds

Synthetic diamonds are diamonds that are chemically and crystallographically identical to naturally occurring diamonds but are created in a laboratory. They have the same optical, thermal, and conductivity properties as natural diamonds. The video mentions synthetic diamonds, stating that they are the same as natural diamonds in terms of hardness and other properties but are formed through laboratory processes rather than geological ones.

💡Obsidian

Obsidian is a naturally occurring volcanic glass that is not a mineral because it lacks a crystal structure. It has the same chemical composition as granite but forms differently due to rapid cooling of lava. The video explains that obsidian was used by prehistoric humans for making tools like arrowheads and knives due to its ability to form very sharp edges.

💡Fool's Gold

Fool's gold is the common name for pyrite, a mineral composed of iron sulfide. It has a metallic luster and a similar cubic crystal structure to gold, which can make it appear similar to gold. However, it is not actual gold. The video clarifies the difference between real gold and fool's gold, noting their distinct colors and composition.

💡Crystal Formation

Crystal formation is the process by which atoms of a mineral arrange themselves into a repeating, specific pattern to form a visible crystal. This process requires specific temperature and pressure conditions and the presence of a fluid to transport the necessary ingredients. The video uses amethyst, a variety of quartz, as an example, explaining that silicon and oxygen atoms arrange in a hexagonal crystal system.

💡Pearls

Pearls are formed through organic processes and are not considered minerals because they do not form inorganically. They are created when an irritant, like a piece of debris, becomes trapped inside a mollusk, which then secretes nacre to cover the irritant, forming a pearl. The video notes that pearls are made of the mineral calcite, or calcium carbonate, and are an example of biominerals.

💡Geodes

Geodes are rock formations that have a hollow interior lined with crystals, often quartz. They form when there is an open cavity that allows minerals to grow inside over time. The video describes geodes as being 'very cool' and explains that they can be found in nature, such as in Utah, and cautions to wear safety glasses when opening them.

💡Ethical Sourcing

Ethical sourcing refers to the practice of ensuring that the origin and production of gemstones and minerals are free from unethical practices, such as child labor, violence, or environmental damage. The video discusses 'blood diamonds' and the Kimberly process, which is an international scheme to certify the origin of diamonds to prevent their sale being used to fund conflict.

Highlights

Rocks are composed of minerals, with granite containing quartz, feldspar, biotite, and muscovite.

All minerals are crystals by definition, with gemstones being cut and faceted mineral crystals.

Rubies and sapphires are the same mineral, corundum, differentiated by color.

Emeralds are a variety of the mineral beryl, with their color coming from chromium impurities.

Hackmanite, a variety of sodalite, exhibits tenebrescence, glowing under UV light.

The Mohs Hardness Scale measures mineral hardness based on scratch ability, with talc at 1 and diamond at 10.

Diamonds are cut using diamond powder on a rotating plate, starting with coarse grit and moving to finer grits.

Diamond grading is based on the Four Cs: color, clarity, cut, and carat weight.

Synthetic diamonds have the same properties as natural diamonds but are lab-created.

Diamonds are not eternal; over millions of years, they will transform into graphite under Earth's surface conditions.

Obsidian is natural volcanic glass with the same chemical composition as granite but lacks a crystal structure.

Fool's gold, or pyrite, is iron sulfide with a golden luster but is not actual gold.

There are over 5,000 known mineral species on Earth, with theoretically up to 9,000 possible combinations.

Minerals in mobile phones, like lithium from spodumene, come from pegmatite rocks found globally.

The Hope Diamond, once thought to be cursed, is now considered a blessing and a centerpiece of the National Gem collection.

Crystals form from atoms arranging in a repeating pattern under specific temperature and pressure conditions.

Pearls are not minerals as they form through organic processes, but they consist of the mineral calcium carbonate.

Gemmy refers to the potential of a mineral crystal to be cut into a gemstone based on its transparency and quality.

Moonstone can get wet without harm, unlike opals, which are porous and can absorb water.

Geodes form from open cavities that allow crystal growth inside, commonly filled with quartz.

Turquoise jewelry is expensive due to the rarity of the gemstone and the labor-intensive process of mining, cutting, and setting.

Rubies are found worldwide, but the most valuable ones come from Burma, particularly the Mogok region.

Blood diamonds are linked to conflicts and are regulated by the Kimberly Process to prevent illegal trade.

Gems are discovered through market scouting and direct acquisition from mines, exemplified by the world's largest sapphirine crystal from Madagascar.

Transcripts

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