Sodalite is an alkaline magnesium aluminum phosphate that occurs as glassy, massive, or granular crystals, typically exhibiting a blue hue. Most sodalite is opaque or translucent, while the transparent varieties are often used as gemstone materials.

Iron pectolite is a phosphate mineral similar to pectolite; when the magnesium in pectolite is replaced by iron, it transforms into iron pectolite.

Transparent gypsum is a type of gypsum whose crystals are transparent due to their well-developed structure.

Fibrous gypsum is also a type of plaster.

Smoky quartz is actually a common variety of quartz. Colorless, pure, and transparent quartz is known as rock crystal, and from this, quartz with a dark brownish (smoky) hue is referred to as smoky quartz. In addition to these, there are also varieties like citrine and amethyst. Among these types, smoky quartz is the least valuable due to its abundant availability. Interestingly, smoky quartz has a unique characteristic: when heated, it loses its color and turns yellow, which is why it’s often mistakenly sold as citrine.

Chalcopyrite is a sulfide mineral of copper and iron, often found together with chalcopyrite or pyrrhotite. It exhibits a metallic luster and appears yellow or bronze-yellow in color.

Chromite is a lead chromate mineral, and the element chromium was first discovered in this very mineral. Chromium is widely used to coat metal surfaces for corrosion protection. Thanks to its vibrant red color, chromite can also serve as a pigment. Today, however, synthetic chromite is typically employed as the primary pigment in paints and coatings. Chromite boasts a diamond-like or glassy luster, making it a remarkably beautiful mineral. Well-developed crystals often exhibit an elongated, columnar shape.

Tourmaline Origin: Afghanistan

Magnesio-tourmaline is a brown tourmaline rich in magnesium.

Magnetite hornblende is a type of hornblende—a ferromagnesian silicate mineral. Many hornblendes develop fibrous crystals, collectively known as asbestos; magnetite hornblende is one such variety of asbestos.

Arsenocopper is a copper arsenide mineral, ranging in color from silvery white to steel gray, and can fade to a pale yellowish-brown, exhibiting a metallic luster.

Bayerite is a carbonate mineral that ranges in color from colorless to white and has a glassy luster; it serves as an ore for extracting aluminum.

Diopside is a common type of pyroxene—it belongs to the silicate mineral group and is a silicate of calcium and magnesium. Diopside occurs in shades of white and varying degrees of green, exhibiting a glassy luster. It typically forms long prismatic crystals, as well as granular or flaky aggregates.

Anorthoclase is a common feldspar-like mineral, a hydrous sodium aluminum silicate. It can be found in basalt, diabase, granite, gneiss, cave formations, and alkaline lake-bottom sediments.

Emerald Origin: Colombia

Nickeloxide is a hydrous nickel arsenate mineral. It occurs in columnar or platy forms, and its crystal aggregates often appear as crusty, earthy, or powdery masses. Colors range from white, gray, pale green, to yellowish-green, with transparency ranging from transparent to translucent, and it exhibits a vitreous luster.

Epidote is a sodium-iron silicate, belonging to the pyroxene mineral group. It ranges in color from green to pale greenish-black and exhibits a vitreous luster.

Cuprite is a copper sulfate mineral and one of the primary ores used for extracting copper. It ranges in color from vibrant green to pale black-green or light green, exhibiting a glassy luster.

Orange-red spessartine garnet, Origin: Africa

Agate is a common silicate mineral—it’s essentially just quartz, sharing many of the same properties. The familiar Yuhua stones we know are actually agate. In mineralogy, agate is also classified as a variety of chalcedony. It comes in a dazzling array of colors, often displaying multiple hues simultaneously. Typically, agate ranges from semi-transparent to opaque. Though considered a lower-grade gemstone, humans have been crafting it into exquisite art objects for centuries. Some agates even contain water inside, known as "water-cave agate." When you gently shake these unique pieces, you can hear the soothing sound of water trickling—truly a fascinating and unusual sight!

Molybdenite is a sulfate mineral formed through the reaction between sulfate solutions and aluminum-bearing minerals; it is hydrated aluminum sulfate. Molybdenite occurs in colors such as white, yellow, and red, exhibiting either a glassy or silky luster, and typically appears as fibrous masses or crust-like formations. Because of its resemblance to efflorescence salts, it was historically known as "hair salt."

Lithiophosphate is a phosphate mineral composed of lithium, sodium, and aluminum, and it serves as a key ore for extracting lithium. It typically appears as white, translucent masses, and high-quality specimens have even been prized by people as gemstones.

Tourmaline Origin: Nigeria

Sodium feldspar is a type of feldspar—a common feldspar mineral classified as an aluminosilicate. Typically, sodium feldspar appears as glassy crystals, which can be colorless or exhibit shades of white, yellow, red, green, or black. It serves as a key raw material in the production of glass and ceramics. Many rocks contain sodium feldspar as a component, and such minerals are referred to as rock-forming minerals.

Triclinic barite is a carbonate mineral composed of barium and calcium, with trace amounts of strontium also present. This mineral ranges in color from colorless to gray or pink, and can be either transparent or translucent.

Mint-colored andradite garnet, Origin: Merelani, Tanzania

Arsenical stibnite consists of antimony arsenide, appearing as a tin-white or reddish-gray mineral with a metallic luster, and occurs in massive forms.

天河石 is a type of feldspar, a variety of green microcline. It is often mistaken for jade. Widely regarded as a gemstone,天河石 features colors ranging from yellowish-green to bluish-green and is typically opaque.

Pyrope-alumina is a variety of purple-red spinel; when garnet contains iron and aluminum, it becomes pyrope-alumina. In fact, pyrope-alumina is one of the most common types of garnet. Typically, pyrope-alumina exhibits colors ranging from brownish red and deep red to pale purple. This gemstone is highly prized for its beauty. Pyrope-alumina, magnesia-alumina garnet, and manganese-alumina garnet often occur together in nature.

Sodium ferrohornblende, also known as sodium hornblende, is a type of hornblende mineral—a sodium-rich iron-bearing silicate.

Crystal—Back left: Citrine, Back right: Lemon Quartz, Front left: Madeira Wine Citrine, Front right: Amethyst. Origin: Brazil

Hornblende is a silicate mineral and a member of the amphibole group, minerals in this group are often referred to as amphibole asbestos. Hornblende crystals typically appear as long prismatic, needle-like, or hair-like structures.

叶蛇纹石 is a type of serpentine—it shares the same properties as serpentine but has a distinct appearance. This phenomenon is known as polymorphism.

Epidote is a potassium-calcium fluorosilicate mineral. Common epidote occurs as glassy, white-to-gray crystals. Structurally, epidote resembles zeolites and often forms alongside zeolites in basalt, granite, and gneiss.

Actinolite is a type of amphibole—a silicate mineral composed of magnesium and iron. Like asbestos, actinolite also features a fibrous structure; however, its fibers are far too weak, which is why it’s not used to manufacture asbestos products.

Amethyst is a variety of quartz—a silicon-oxygen mineral—and shares the same physical properties as quartz itself. Amethyst exhibits its distinctive purple hue due to the presence of iron (or manganese or hydrocarbons), whereas other quartz varieties, even those containing iron, simply don’t have enough to develop this color. Thus, while amethyst can be considered a gemstone, it isn’t particularly precious. Interestingly, heating can cause amethyst to fade or even turn yellow.

White crystal embodies energy that is most representative among all crystals—possessing the widest range of functions, the broadest applications, and offering the greatest assistance to people. It rightfully stands as the "king of crystals." Known for its ability to enhance memory and promote focus, white crystal also harmonizes all forms of thermal energy while miraculously purifying harmful radiation.

Illite is a mica-like clay mineral with a layered structure, also known as hydromica. It can be used as a ceramic raw material, as well as in the manufacture of cosmetics or plastics; highly pure illite is even employed in the paper industry and other industrial applications such as spraying coatings and radiation shielding.

Fluorite, also known as fluorspar, is a common halide mineral composed of calcium fluoride and serves as an important source for extracting fluorine. Fluorite comes in a wide variety of colors, and it can even be transparent and colorless. Transparent, colorless fluorite is often used to produce specialized optical lenses.

Tricolor Tourmaline, Origin: Nigeria

Anhydrite is a sulfate mineral composed of anhydrous calcium sulfate, distinguished from gypsum by its complete absence of water of crystallization. In humid environments, anhydrite readily absorbs moisture and transforms into gypsum. As an important rock-forming mineral—meaning it’s a common constituent in many types of rocks—it typically forms primarily in saline lakes. Anhydrite is widely used to produce fertilizers, cement, and plaster.

Diaspore is an aluminum oxide mineral that typically appears white, gray, or colorless; however, when impurities are present, it can exhibit shades of red, brown, and other hues. It has a glassy luster and is remarkably hard. Diaspore is widely found in bauxite deposits, lateritic soils, and certain types of rocks. This mineral can be used as a refractory material, as well as a key raw material for extracting aluminum.

Uranium ores can appear in earthy, powdery forms, as well as in massive, stalactite-like, kidney-shaped, and other varieties. Some earthy uranium ores are known as uraninite, while the massive ones are called pitchblende. In addition to being used to extract uranium for the nuclear industry, these ores can also yield radium and other rare earth elements.

Corundum—purple and pink hues come from Madagascar, blue ones from Kashmir, while chartreuse yellow-green and white varieties originate in the United States.

Chalcocite is a sulfosalt mineral containing copper, iron, zinc, and silver. It is an important copper ore mineral and can also serve as a significant silver-bearing ore mineral. The copper in chalcocite can be partially replaced by other elements; when the amount of these newly substituted elements reaches a certain threshold, chalcocite transforms into other minerals, such as argentite, tetrahedrite, tennantite, and more. Chalcocite typically appears gray to black, with a slight metallic luster, and usually occurs in massive or granular forms. It is commonly found alongside other copper minerals.

Mica is a general term for a group of hydrous potassium aluminum silicate minerals, all of which share one common feature: a layered structure. There are many types of mica, including biotite, chloritoid, phengite, glauconite, illite, lepidolite, sericite, muscovite, paragonite, and annite, among others. Mica can be found in three major rock categories—igneous, sedimentary, and metamorphic rocks—and is a widely occurring mineral.

Emeraldite – Back left: Aquamarine, Origin: Brazil; Back right: Golden Beryl, Origin: Brazil; Front left: Red Beryl, Origin: Utah, USA; Front right: Emerald, Origin: Colombia

Soapstone is a silicate mineral that is so soft it can be easily cut with a knife and has a delightfully smooth, slippery texture. However, when dry, soapstone becomes brittle. This versatile mineral comes in a variety of colors, including white, yellow, green, red, and blue. Soapstone belongs to the smectite mineral group—a family of minerals widely used as adsorbents and fillers in the chemical and textile industries.

Hematite, also known as limonite, is a widely distributed iron oxide—what we commonly see as rust is essentially composed of this mineral. Typically, hematite forms under weathering conditions from other iron ores, such as pyrite and magnetite. It can also be formed through sedimentary processes at the bottom of oceans or lakes. As a relatively important iron ore, hematite is not only used for extracting iron but is also employed as a yellow ochre pigment.

Pink tourmaline, Origin: Afghanistan

Vermiculite is a clay mineral similar to montmorillonite, characterized by its layered silicate structure. It typically forms through hydrothermal alteration or weathering of biotite. Sometimes it appears as coarse, biotite-like crystals—what’s known as vermiculite’s "biotite pseudomorph"—while at other times it becomes so fine that it resembles soil. When vermiculite is heated to 300°C, it expands up to 20 times its original size and curls into a distinctive shape. This expanded form bears a striking resemblance to leeches (commonly called "mawang" in some regions), which is how it earned its name.

Barite is the most common mineral of barium, composed of barium sulfate. It occurs in hydrothermal veins as well as in limestone and clay deposits formed by the weathering of limestone. Barite crystals typically grow into large, tubular shapes, and when these crystals cluster together, they can sometimes form rosette-like structures or forked crystal masses—known as capillary barite.

Natural platinum is the naturally occurring mineral form of the element platinum, and it’s also commonly known as white gold. Most of the white gold jewelry and industrial-grade platinum we encounter today are derived from natural platinum. Platinum boasts exceptional resistance to corrosion and oxidation, along with a low thermal expansion coefficient, making it indispensable in numerous critical applications.

Natural gold is the native mineral form of the element gold—essentially, it refers to gold nuggets that occur naturally in the environment, commonly known in folklore as "dog-head gold." Natural gold can appear in various shapes and forms, such as dendritic, granular, flaky, or massive structures. There have even been instances where natural gold specimens weighing over 200 kilograms were discovered.

Native copper refers to various naturally occurring, flaky, platy, or massive aggregates of the copper element found in nature. Unoxidized native copper has a reddish surface with a metallic luster. However, due to oxidation, native copper typically appears brownish-black or greenish in color.

Silicide, also known as chrysoberyl-like stone, typically appears in short columnar or granular forms, occurring in colors such as colorless, yellow, pale red, and brown, with a glassy luster. As a rare mineral, silicide is composed of beryllium silicate. It boasts a high refractive index, making it exceptionally bright—so much so that it’s sometimes mistaken for diamond. Silicide is prized as a gemstone and is often found alongside emerald and chrysoberyl.

Striped feldspar is a type of feldspar formed when two feldspars with different compositions—labradorite and orthoclase or microcline—grow closely together. In the molten, fiery state, sodium-rich and potassium-rich feldspars mix uniformly; however, as they cool, the two crystalline structures become distinctly separated, creating striking striped patterns.

Ampelolite is a variety of the plagioclase series within the feldspar minerals, distinguished by its unique iridescent sheen. This iridescence in ampelolite closely resembles the shimmering colors found on a pigeon's feathers—hence the mineral's Greek name, which literally means "pigeon."

Polyhalite is a sulfate mineral that is commonly found alongside anhydrite and halite. Polyhalite crystals are rare, and its aggregates typically occur as granular masses or in fibrous and flaky forms. Some specimens are transparent and colorless, while others exhibit hues such as white, pale gray, pale yellow, or reddish tones—though most lack any significant luster.

Phlogopite is a type of mica mineral, specifically an aluminum silicate containing iron, magnesium, and potassium. When the iron content in phlogopite is relatively low, it can serve as an excellent electrical insulator, making it highly valuable for various applications.

Sulfantimonite is a sulfide mineral composed of silver, copper, and antimony. It has an iron-black color with a metallic luster and typically occurs as tabular crystals or massive forms. Sulfantimonite is an important ore for extracting silver.

Pale yellow and mint green tourmaline. Origin: Mozambique, Afghanistan

Sodium mica is a type of mica that resembles white mica; it is a silicate composed of sodium and aluminum. Sodium mica is widely found in schists, phyllites, gneisses, quartz veins, and fine-grained sedimentary rocks.

Lead jarosite is a widely distributed iron and lead sulfate mineral, found in the oxidation zones of lead deposits. It is an important lead-bearing mineral used for extracting lead. Lead jarosite appears yellowish-brown, with either a glossy or dull luster, and typically occurs in massive forms.

Plagioclase is a series of feldspar minerals, including albite, andesine, labradorite, bytownite, and anorthite. Most varieties of plagioclase exhibit fine, parallel stripes on their surfaces, and some even display iridescent blue or green hues—both phenomena caused by their unique twin structures. Plagioclase is widely used in the production of glass and ceramics.

Pyrolusite is an oxide of barium and manganese, and it serves as a crucial ore for extracting manganese. Unlike many minerals that form deep underground, pyrolusite is a secondary mineral that develops under near-surface conditions—meaning it originally existed as a different mineral but later transformed into its current form under specific environmental conditions.

Sodalite is a member of the feldspathoid mineral group, classified as a sodium aluminum silicate containing chloride. Sodalite encompasses varieties such as hydrosodalite, hauyne, and lazurite, each displaying distinct colors. Hauyne, often found as inclusions in volcanic ejecta, typically appears in shades of gray, brown, and blue. Meanwhile, lazurite not only comes in vibrant blue hues but also in white, gray, and even green tones.

Skutterudite is a family of arsenide minerals composed of cobalt and nickel, including minerals such as skutterudite, nickelskutterudite, paarskutterudite, and bismuthnickelarsenide. Although these skutterudites share similar chemical compositions and closely resemble each other in shape and color, they require specialized methods for differentiation. Skutterudite typically ranges from tin-white to steel-gray, sometimes with a slight grayish tinge, and exhibits a metallic luster.

Sericite is a type of mica, belonging to the group of silicate minerals with a layered structure. It has a wide range of applications in industries such as rubber, plastics, coatings, paints, ceramics, insulation, cosmetics, pigments, papermaking, and metallurgy. Sericite crystals are flaky in shape, while their aggregates form massive structures, exhibiting colors like gray, purplish rose, and white, with a silky luster.

Calcium-iron garnet is a type of garnet that contains calcium and iron, hence its name. Calcium-iron garnets come in a variety of colors and are known for their high dispersion and refractive index—so high, in fact, that they even surpass those of diamonds. Among calcium-iron garnets, the yellow and green varieties are particularly stunning and are prized as gemstones; the pale yellow ones are specifically referred to as demantoid garnets.

If calcium-iron garnet is rich in titanium, it becomes the titanium-rich variety—titanogarnet. Titanogarnet is also a type of garnet.

Sanidine is a type of feldspar that can sometimes be found directly in surface rocks. It appears as colorless to white, glassy crystals.

Aquamarine Origin: Brazil

Pyrolusite, composed of manganese dioxide, is a common manganese mineral. It contains 63.19% manganese and serves as an important manganese ore. Pyrolusite is remarkably soft—softer even than a human fingernail—and its color ranges from light gray to black, with a metallic luster. If you touch it with your hand, it’ll leave your fingers looking as dark as coal.

Anatase is one of the three minerals composed of titanium dioxide, the other two being rutile and brookite. We’ve already introduced rutile. Anatase shares similar physical properties, formation conditions, and applications with rutile, and it can even transform into rutile over time.

Bayerite is an aluminum hydroxide mineral and serves as the primary component in bauxite deposits. Bayerite crystals are extremely fine, often aggregating into nodular, bean-like, or earthy masses. Typically white with a glassy luster, they may turn reddish when impurities are present. These minerals are mainly secondary products formed through the weathering of aluminum-bearing minerals such as feldspar.

Amphiboles are common silicate minerals that serve as either the primary or secondary constituents of many rocks, leading people to refer to them as rock-forming minerals. Amphibole crystals typically exhibit a slender, needle-like or fibrous shape, and their color can range from white to green depending on the specific chemical composition they contain. Amphiboles represent a broad group of minerals, which can be further classified into numerous varieties based on their distinct chemical makeup—such as actinolite, tremolite, common hornblende, blue amphibole, sodium amphibole, sodium-iron amphibole, and more.

Sphalerite is a zinc sulfide mineral containing 67% zinc by weight, making it the primary ore mineral used for extracting zinc. Sphalerite also contains numerous other elements, such as iron, manganese, cadmium, indium, thallium, gallium, and germanium. In some sphalerite specimens, the iron content can rise as high as 30%, at which point the mineral is referred to as "iron-rich sphalerite." The higher the iron content, the lower the mineral's transparency—and its luster shifts progressively from adamantine (diamond-like) to metallic.

Pyrochlore is an oxide mineral and the primary source for extracting niobium. Its composition includes elements such as niobium, sodium, calcium, as well as rare earths, uranium, thorium, zirconium, titanium, and more—making it a complex oxide mineral. As a result, tantalum, rare earth elements, and even uranium and thorium can also be extracted from it. Pyrochlore typically appears as brown-to-black glassy crystals or irregularly shaped masses, exhibiting resinous or diamond-like luster and being slightly translucent. Interestingly, pyrochlore has a peculiar property: when heated over a flame, it instantly turns green.

Serpentine is a general term for hydrous, magnesium-rich silicate minerals, such as antigorite, chrysotile, and lizardite. These minerals typically exhibit greenish hues, though they can also appear in shades of pale gray, white, or yellow. They are named for their distinctive appearance—often alternating between vibrant greens and soft grays, resembling snake skin.

Crossite is a silicate mineral named for its distinctive cross-shaped appearance. Hard yet brittle, crossite exhibits a dull luster and typically appears in shades of dark brown. Rarely, transparent specimens of crossite are prized as gemstones. Due to its unique shape, it’s often crafted into decorative items.

Gypsum is a common sulfate mineral with significant applications. Gypsum crystals typically form in platy or columnar shapes, ranging in color from white to gray; when impurities are present, they may take on shades of pale yellow or light brown, exhibiting a glass-like luster. Gypsum is also widely used as a filler in papermaking and paint production, serves as a setting retarder in chemical manufacturing, and acts as a fluxing agent in metallurgy. China is a country rich in gypsum resources.

Garnet is a group of silicate minerals that come in many varieties, such as grossular, andradite, pyrope, uvarovite, almandine, spessartine, and more. Garnets can be colorless, black, or exhibit a wide range of reddish and greenish hues. Synthetic yttrium aluminum garnet is used as a material for lasers, while natural garnets are commonly employed as abrasives.

Asbestos is a group of fibrous silicate minerals, and there are many varieties within this category. A defining characteristic of these minerals is their ability to split into long, slender, and flexible fibers—fibers that can be readily utilized by humans. Typically, when we refer to asbestos, we’re talking about specific types of chrysotile and amphibole minerals. Asbestos fibers exhibit remarkable properties such as flexibility, resistance to acids and alkalis, high-temperature durability, and excellent insulation capabilities. Some varieties of asbestos even possess notable filtering properties.

Graphite, also known as pencil lead or blacklead, is a mineral composed entirely of carbon. It ranges in color from dark gray to black, is opaque, and remarkably soft—giving it an oily texture that leaves a distinct black mark on the skin. Despite its greasy feel, graphite exhibits excellent electrical conductivity. The applications and demand for graphite are vast: it’s used to manufacture crucibles, lubricants, electrodes, coatings for casting molds, neutron moderators in nuclear reactors, and even serves as a key raw material in the production of synthetic diamonds. Interestingly, graphite can be artificially produced by processing anthracite coal or petroleum coke.

Rock salt is naturally occurring sodium chloride, and since both are formed when saltwater evaporates in enclosed basins to create salt deposits, it’s also known as a halide mineral. Its crystals are cubic in shape, often clustering together into massive, granular, stalactite-like, or halo-shaped formations. Freshly broken surfaces exhibit a glassy luster, which gradually transforms into an oily sheen upon exposure to moisture. Beyond being a vital food ingredient for people, rock salt also plays a crucial role in various industrial applications—such as extracting sodium and chlorine, and serving as a key raw material for producing hydrochloric acid, alkalis, and more.

Brucite is a mineral composed of magnesium hydroxide, also known as hydromagnesite. It typically occurs as crystals, platy aggregates, or fibrous masses. Brucite is remarkably soft; in fact, fibrous brucite can be peeled into elastic, ribbon-like strips. While brucite is usually white, it may also appear in shades of green, brown, gray, and more, exhibiting a glassy luster. Brucite is widely used as a refractory material and can also serve as a source for extracting magnesium.

Pyrolusite is an alkaline manganese oxide mineral, serving as a manganese ore second in importance only to pyrolusite and psilomelane. It typically appears in dark gray to black hues, often forming parallel bundles of acicular or fibrous masses, though it can also occur in granular or stalactitic forms.

Ilmenite is an oxide mineral of iron and titanium, serving as the primary ore for extracting titanium. It is heavy in weight, ranging in color from gray to black, with a slight metallic luster. Its crystals typically form plate-like shapes, and when aggregated, they occur in massive or granular forms.

Tantalite is the primary ore mineral used to extract the metal tantalum. Occasionally, tantalum in tantalite can be replaced by niobium, at which point it becomes indistinguishable from columbite. Thus, tantalite can also be regarded as a tantalum-rich variety of columbite. However, tantalite is slightly harder and denser than columbite.

Barite, formerly known as baryte or barium carbonate mineral, is a carbonate mineral. Although barite is quite rare in its distribution, it serves as a secondary ore of barium—while the primary source of barium is the mineral barite itself. Barite crystals typically form in massive, spherical, reniform, fibrous, or grape-like aggregates. It occurs in colors such as white, gray, and pale yellow, exhibiting a glassy luster, and under cathode-ray irradiation, it emits a faint blue fluorescence.

Chalkopyrite is a mineral composed of copper sulfide, containing 66% copper and serving as a key ore for extracting copper. It exhibits a striking blue color with a metallic luster, typically occurring in flaky forms or as a thin film coating other minerals or rocks—sometimes even resembling a patch of soot. Chalkopyrite is primarily found near other copper deposits.

Thorite is a thorium silicate mineral and one of the most significant thorium-bearing minerals. Thorium in thorite is often replaced by elements such as uranium, calcium, and cerium, making its varieties useful for extracting these elements as well. Thorite typically occurs in granular or massive forms and can exhibit colors ranging from black and brown to yellow and orange. It is translucent with a glassy luster.

Euxenite and pyrochlore look identical at first glance, but their chemical compositions differ slightly—a phenomenon known as isomorphism. We know that atoms in a crystal are arranged in a highly ordered, rule-based pattern. However, when some of the original atoms—say, type A—are replaced by others (type B) with similar properties, a mixed crystal structure emerges, combining both types of atoms. Such crystals, when compared to their pure counterparts, exhibit this unique form of isomorphism. Euxenite and pyrochlore are perfect examples of this, being fully isomorphic; the only noticeable difference is that euxenite is slightly heavier than pyrochlore, while their other physical and chemical properties remain remarkably similar.

Epidote is a silicate mineral composed of titanium and calcium, found as a component in many types of rocks (igneous rocks). Epidote typically occurs as individual crystals, which are plate-like in shape. It exhibits a vitreous luster and comes in hues ranging from yellow and brown to green, black, and red. Epidote can be refined to extract titanium, or it can even be used as a gemstone.

Realgar is a sulfide mineral containing arsenic and sulfur, making it an important ore of arsenic. It often occurs alongside orpiment. When exposed to sunlight over time, realgar gradually decomposes into orpiment, turning into a powdery substance. Well-formed realgar crystals are typically short and columnar, while aggregates appear granular or massive. It exhibits a vibrant red color with a greasy luster.

Wollastonite is a very soft silicate mineral commonly used by people for purposes such as lithographic pencils, tailor's chalk, or carving small objects. In China, it is also widely known by another name: Shoushan Stone (or Qingtian Stone, Changhua Stone). Pure wollastonite exhibits white, gray, or yellowish tones with a waxy luster, giving it a smooth, slippery feel when touched. This versatile mineral has numerous industrial and agricultural applications—for instance, it can serve as a filler in the production of paper, pigments, rubber, paints, plastics, and even as an ingredient in pesticides. Moreover, high-quality wollastonite is prized as a raw material for crafting exquisite art pieces.

The most common mineral in Earth's crust is feldspar, which can even be found abundantly on the Moon and in meteorites. Within the top 15 kilometers of the Earth's crust, feldspar accounts for as much as 60% of the total crustal weight. As a primary constituent of igneous rocks, feldspar is also widely present in metamorphic and sedimentary rocks. Feldspar is an aluminum silicate mineral containing calcium, sodium, and potassium—and it comes in many varieties, including albite, anorthite, barium feldspar, barian plagioclase, microcline, orthoclase, and sanidine. All these feldspars exhibit a glassy luster and display a dazzling array of colors; some even boast mesmerizing play-of-color or iridescence, making them highly prized as gemstone materials.

Corundum is an aluminum oxide mineral, and in the natural world, its hardness ranks second only to diamond. The sapphires and rubies we often hear about are actually high-quality varieties of corundum. Corundum is widely distributed in nature, yet it is also highly susceptible to weathering, easily transforming into other minerals over time. It typically appears as columnar crystals, massive forms, or rounded granules, found in igneous, sedimentary, and metamorphic rocks alike.

Chalcedony is actually a type of quartz—it’s a variety of cryptocrystalline quartz. It typically forms in nodular, mammillary, or stalactitic shapes, exhibiting a waxy luster and a remarkably fine, fibrous texture. Chalcedony comes in a wide range of colors, most commonly pale blue-white, gray, yellow, or brown. Some chalcedony nodules even contain trapped water and air bubbles, making them particularly intriguing. In terms of physical properties, chalcedony is identical to quartz. People often regard chalcedony as a gemstone.

Malachite is a secondary copper ore (with primary copper ores like chalcocite and chalcopyrite being the main ones), yet despite being secondary, it is widely distributed. Known for its strikingly vibrant and distinctive color, malachite is often used as a decorative material—and even treated as a gemstone—due to its visual appeal.

The material is sourced from the internet. ​