#crystal structure

[nemfrog]

Space lattice with crystallographic axes. Crystalline form and chemical constitution. 1926.

Internet Archive

[miamaimania]

"Hematite Iron Rose" by Juan - Metallic petals form intricate layers, capturing the mineral's natural elegance.

[materialsscienceandengineering]

Scientists create a hexagonal diamond that could be even harder than the real thing

To misquote a famous song, "Diamonds are industry's best friend." Cubic diamond is the hardest mineral on Earth and is used in everything from precision cutting tools to high-performance semiconductors as well as expensive jewelry. But there is a rare and potentially tougher form called hexagonal diamond (HD), which has long been the subject of theories and debate over its actual existence. But now researchers from China claim to have created this elusive form of carbon in the lab. Hexagonal diamond (also known as lonsdaleite) is usually found at sites of meteorite impacts. But because the quantities are so small and mixed with minerals, some scientists doubted it was a distinct material. In a paper published in the journal Nature, researchers describe how they made a bulk piece of pure HD using extreme pressure and heat.

Read more.

[toyastales]

Geology Rocks: Dravite Tourmaline

Dravite Tourmaline is one of the three major types of Tourmaline, along with Schorl (black) and Elbaite (multi-colored).  Dravite Tourmalines are typically brown, yellow or green, and are rich in magnesium and sodium. Tourmaline is found around the world.  Dravite is one of the main varieties and comes in several colors, most notably yellow, brown and green. Notable deposits for Dravite Tourmaline include Australia, Austria, Brazil, India, Italy, Nepal, Switzerland, Tanzania, and the United States.

Spiritual Meaning:

Dravite is a strong grounding stone. It has a soothing, relaxing, and reassuring effect on your body, as well as on your heart and mind. Dravite Tourmaline gently nurtures self-compassion and healing after trauma. If we have become emotionally numb, Dravite Tourmaline helps us to feel again.

[ahedderick]

Musing to myself; well, the structure of a molecular diamond is super-simple (all Carbon all the time); I wonder how quartz is put together?

Now I'm hip-deep in a rabbit hole and hmm. SiO2 but really SiO4 but really

"it is worth mentioning that neighboring motifs share one SiO4 tetrahedron to form a group of 5 tetrahedra. As exemplified in the lower part of Fig.4.04 for motif b (multicolored with a blue center), each motif is surrounded by three motifs of the other type (orange, red, purple). That way each of the SiO4 tetrahedra is part of motif a and motif b. (Right now it might not clear what the point about it is, but it is an important finding and we will come back to this later)."

Oop, now we're defining helixes and chirality.

In fairness, this is actually an excellent article; tons of diagrams and their trying to address how the crystal comes together from multiple points of view. The only flaw here is in the reader, who did not sleep all that well last night and decided to learn about crystal structures at 7am on a rainy Sunday morning.

[materiallugy]

Miller Indices and Lattice Planes

Have you ever wondered how scientists talk about the microscopic building blocks of materials? Enter the world of Miller indices and lattice levels, a language that reveals the secrets of atomic arrangements within crystals. Imagine visualizing levels of atoms stacked like bricks, each level described by a unique set of numbers that reveal its orientation and spacing.

How to determine Miller Indices?

Imagine the crystal lattice with three axes: These axes represent the basic building blocks of the crystal's structure. In a cubic crystal, for example, the axes are all perpendicular to each other and of equal length.

Identify a plane: This plane can cut through the lattice in any direction, intersecting the axes at different points.

Find the intercepts: For each axis, measure the distance from the origin to the point where the plane intersects it. If the plane doesn't intersect an axis, then the intercept is considered to be "at infinity" and is represented by a zero.

Take the reciprocals: For each non-zero intercept, take the reciprocal (flip it over).

Simplify and normalize: If any of the reciprocals have a common factor, divide them all by that factor to get the smallest possible integers.

Put the numbers together: The resulting three integers, enclosed in parentheses (h k l), are the Miller indices for that plane.

Read more:

Miller Indices and Lattice Planes - Materiallugy

Miller indices are a set of three integers (h, k, and l) used to represent planes and directions within a crystal lattice.

[sciencenewsforstudents]

Why we should stop ignoring the life stories of minerals

All pure diamonds are the same mineral. But they didn’t form the same way. One scientist thinks it’s time to talk about the life stories of such rocks.

WASHINGTON, D.C. — Every rock has a story. Understanding how it formed can tell scientists about the environment that surrounded the rock at its birth. But when scientists classify the minerals that make up rocks, they leave out the details of how those minerals formed. One scientist wants to change that. He wants to give minerals back their biographies. Knowing that history, he says, could help scientists understand more about our planet — and many others.  

Minerals are solid substances that occur in nature. Up close, their molecules form regular, three-dimensional crystal patterns. A diamond is one example. Diamonds most often occur as cubic crystals. This means their atoms are stacked in repeating cube shapes. The whole rock (which can be made of one or more minerals) may end up with sharp edges too. It might be a cube, or it could be an octahedron, a shape with eight flat faces.  

Diamonds are a good example of how minerals with the same name can have different histories, says Andrew Christy. He’s is the curator of minerology at Queensland Museum in Brisbane, Australia. The big diamonds found in jewelry formed more than 160 kilometers (100 miles) below Earth’s surface, in the mantle. Heat and pressure there smushed carbon atoms together into cubes. That created diamond crystals. The ones we dig up today have been pushed to the surface through violent volcanic eruptions.

But diamonds can form elsewhere in the universe, as well. Tiny diamonds, for instance, form in meteorites crashing to Earth from space. Some of those meteorites have carbon atoms in them, Christy explains. When a meteorite blasts through Earth’s atmosphere, it can generate shockwaves of heat and pressure. “Those shockwaves passing through that carbon [in the meteorite] will create tiny, tiny diamonds,” Christy explains.

Both of these rocks are diamonds. Based on their crystal structure, mineralogists would classify them the same. But Robert Hazen says scientists lose a lot when they take away the story of a mineral’s birth. “Natural minerals are storehouses of information,” he says. “They’re time capsules with vast amounts of information we have not yet explored.” Hazen is a mineralogist at the Carnegie Institution’s Geophysical Laboratory in Washington, D.C.

[data-and-vision]

Zeolite (faujasite) structure