Specimen at a glance
| Mineral | Quartz |
|---|---|
| Chemistry | SiO2 |
| Mohs hardness | 7 |
| Crystal system | Trigonal |
| Locality | Mexico |
| Form | Raw / rough |
| You receive | The exact specimen pictured |
About this specimen
This compact specimen pairs two common but visually distinct minerals on one piece: clear quartz (silicon dioxide) points alongside scattered tan calcite (calcium carbonate) crystal growth. The two minerals often form together in the same mineral-rich cavities, with calcite frequently crystallizing after quartz as conditions and fluid chemistry shift underground — seeing both on a single specimen is a small window into that layered formation history. It was sourced from Mexico, a country with a long mining history and numerous productive quartz and calcite localities.
The contrast between the clear, glassy quartz points (Mohs 7) and the softer, warmer-toned calcite growth (Mohs 3) gives this small specimen real visual and textural character despite its size. Approximately 2 x 1.75″, it’s an easy, affordable way to see two classic minerals together on one piece.
A nice pick for a starter mineral collection, a teaching specimen, or anyone who likes seeing how different minerals interact on the same matrix.
Inside the Calcite
One of the most common minerals on Earth — and one of the only ones you can prove is calcite with nothing but a coin and a drop of vinegar.
The story: Calcite crystallizes out of calcium-rich water almost anywhere conditions allow — caves, hydrothermal veins, sedimentary pockets — which is why it shows up in more shapes than almost any other mineral: sharp dogtooth points, flat nailhead rhombs, honey-gold masses, even the travertine that lines old hot springs. Every one of those forms is chemically the same mineral, just grown under different conditions.
Why collectors chase it: Calcite is the classic demonstration of birefringence — a clear piece laid over printed text splits the letters into a visible double image, a party trick that only a handful of minerals can do. Add in the sheer range of natural color and habit (the golden-toned Ohio pieces get their warmth from iron staining) and it’s an easy mineral to build a whole sub-collection around.
Care: This is the one to handle more carefully than most of the shop: at Mohs 3 it scratches under a fingernail-plus-effort, it splits cleanly along three flat planes if dropped (perfect rhombohedral cleavage), and it will visibly fizz on contact with vinegar or other mild acids — keep it away from acidic cleaners and store it apart from harder stones that could scratch it.
Inside the Quartz Crystal
One mineral species, a thousand looks — quartz is the shape-shifter of the mineral world.
The story: Quartz is the second most abundant mineral in Earth’s crust, and it crystallizes in nearly every rock-forming environment on the planet — which is exactly why it shows up in this shop as clear points, milky clusters, smoky towers, ghostly phantoms, and druzy-crusted matrix, all built from the same simple formula.
Why collectors chase it: Because one species covers this much ground: a single collection can hold a dozen genuinely different-looking quartz pieces without ever repeating a mineral. Phantom growth lines, smoky color zoning, and druzy crusts each record a different chapter of how that particular crystal grew.
Care: Quartz shrugs off scratches and most chemicals at Mohs 7, but avoid sudden temperature swings (a hot dishwasher after a cold shelf can crack a large piece) and clean with a soft, dry cloth.
Quartz: the science
- Every natural quartz crystal has a six-sided prism capped by a point, the same trigonal geometry whether it is a thumbnail or a meter long.
- Quartz is piezoelectric: squeeze it and it produces a tiny voltage. That property is why quartz keeps time in watches and electronics.
- At Mohs 7 it scratches glass and steel, which is why quartz sand is the main abrasive in nature and why quartz outlasts almost everything on a beach.
Go deeper
Want the full story on quartz: how it forms, how to identify it, and what makes a great specimen?
Questions about this piece
What is quartz?
Quartz is crystalline silicon dioxide and one of the most common minerals in Earth’s crust. Clear, well-formed points and clusters grow in open cavities and veins where silica-rich fluids had room and time to crystallize.
Where was it found?
This piece comes from Mexico. We list a locality whenever it is known, because where a mineral formed is part of its story and its value.
How hard is it, and how should I care for it?
It rates 7 on the Mohs scale. Quartz is Mohs 7 and very durable. Dust with a soft brush or rinse in lukewarm water and air dry. Avoid knocking points together and avoid sudden temperature changes.
Is this the exact piece I will receive?
Yes. This listing was photographed individually, and you receive the exact piece shown in the photos.
