Short answer: faden quartz is ordinary quartz, SiO2, with a milky white line running through it. "Faden" is German for thread. The line is a resealed scar: the crystal grew across a crack in the rock, was pulled apart again and again as the crack slowly widened, and each time mended itself, trapping a trail of tiny fluid and gas bubbles. That repeated stretching is also why most faden crystals are flat, the shape dealers sell as "tabby" quartz.
What exactly is the white thread?
Look into a good faden and you see a soft, slightly feathery white band, usually running across the width of a flat crystal from one edge to the other. It is not a separate mineral and it is not a crack you can feel. According to the New Mexico Bureau of Geology's mineral symposium abstract, the faden consists of tiny oriented crystals of quartz that appear white because of water and gas inclusions.
That makes faden quartz chemically identical to a clear point: silicon dioxide, hardness 7, and the same trigonal crystal structure. Webmineral gives quartz a composition of 46.74 % silicon and 53.26 % oxygen. The faden adds no new element. What it adds is a record of movement in the rock, preserved in the only place it could be preserved: inside a growing crystal.
How does faden quartz form, step by step?
Mineralogist Amir Akhavan's Quartz Page lays out the mechanism clearly. Reduced to steps:
- A crack opens in the host rock. Small quartz crystals start growing on its walls.
- A crystal bridges the gap. One crystal grows until it is attached to both walls at once.
- The crack keeps widening. The crystal, held at both ends, ruptures.
- The break reseals. Fresh quartz fills the fracture, and the crystal is again connected to both walls.
- Repeat. Each cycle of widening, rupture and regrowth leaves a scar of liquid and gas inclusions. Stacked together, the scars become the thread.
The interesting part is why quartz is so good at this. When quartz breaks it does not leave a flat surface parallel to a crystal face; it leaves an irregular conchoidal fracture, like broken glass. The Quartz Page explains that such a surface is thermodynamically very unstable and grows very quickly in a saturated solution, much faster than any normal crystal face. That burst of quick growth is what lets the crystal keep up with the moving walls and stitch itself back together.
What the thread says about the crack
The thinness of the line is evidence in itself. If the crack had opened in a few large jumps, for example in earthquakes, the two halves would have separated too far to reconnect during the short phase of fast growth, and each would have finished as a normal crystal. A thin, continuous thread therefore points to a widening that was more or less continuous. The Quartz Page also shows a Waziristan crystal whose faden curves in an arc, because the two rock walls slid sideways relative to each other while they separated.
Why are faden crystals flat?
Quartz normally grows fastest along its c-axis, from base to tip, which is why a typical point is long and six-sided. In a faden crystal attached across a crack, the fast repair growth happens perpendicular to the crack walls. If the crystal lay parallel to the walls, that direction is across the prism, so the crystal ends up wider than it is tall: a flattened, platy, tabular shape. The Quartz Page notes that the faden can be seen best in crystals that grew parallel to the wall, and that a faden running along the c-axis does not produce the flat look at all.
The same source documents other oddities: crystals with skewed or rhomb-like cross sections where the thread runs at an angle to the axes, and "Messerquarz" (knife quartz) from the Ramsbeck lead and zinc mine in Germany's Sauerland, which turns out to be platy faden quartz. For how habit and growth speed shape crystals in general, see crystal habits.
Is all tabby quartz faden quartz?
No, and this is the most useful thing to know before buying. "Tabby" is a trade word for tabular, flattened quartz. The Quartz Page's chapter on the Ouachita Mountains says faden specimens there are sometimes sold as "tabbies" if the faden is not clearly visible, but not all "tabbies" are faden quartz. Quartz can grow flat for other reasons, so the label "tabby" proves nothing about a thread.
The reverse is also true. A faden crystal does not have to be flat. The Quartz Page illustrates a double-terminated rock crystal from Mont Chaz Dura in Italy's Val d'Aosta that is a faden quartz despite its conventional shape. The rule for a buyer is simple: the thread is the feature, so look for the thread, not the shape.
Faden quartz versus phantoms and other inclusions
Faden quartz is sometimes confused with other "line inside a crystal" pieces:
| Feature | Faden quartz | Phantom quartz | Resealed fracture |
|---|---|---|---|
| What the inclusion traces | The path of a crack the crystal grew across | The outline of an earlier crystal tip | A random break later sealed with new quartz |
| Shape of the line | Thin band crossing the crystal, often edge to edge | A pyramid or shell parallel to the faces | Irregular veil, often iridescent |
| Typical crystal shape | Often flat, tabular | Normal prismatic point | Any |
| Material in the line | Fluid and gas inclusions | Chlorite, hematite, clay or color zoning | Fluid inclusions |
A phantom copies the faces of the crystal; a faden cuts across them. A resealed fracture wanders; a faden runs as a band from one attachment point toward the other.
Where does faden quartz come from?
The geology that makes faden needs rock that opens slowly and steadily while quartz-bearing fluid keeps flowing. That describes alpine-type fissures, which the Quartz Page's alpine fissure chapter says typically open and widen slowly; there faden quartz is found mostly in weakly metamorphosed sedimentary rocks like slates and phyllites.
- Pakistan. The Quartz Page says lots of faden quartzes come from Waziristan. These are the crystals most buyers meet: water-clear, flat plates with a milky thread. The broader mineral picture of the region is in our Pakistan origin guide.
- Arkansas, USA. The New Mexico abstract lists Saline County, Arkansas among the noted localities, along with Waziristan, Graubunden in Switzerland and Quebec in Canada. The Quartz Page's own type example of faden quartz is a scan of a specimen from Arkansas.
- Switzerland and the Alps. Piz Beverin in Graubunden has produced instructive specimens, including pairs of faden crystals growing at right angles to each other.
- Afghanistan and Mexico. The Quartz Page shows a distorted faden crystal from the Kuar Valley, Afghanistan; the abstract mentions micro faden crystals, seldom more than 2 or 3 mm, inside quartz-lined geodes in Chihuahua, Mexico.
Arkansas context
The Arkansas Geological Survey describes the Ouachita Mountain crystals as hydrothermal vein quartz filling cavities and fractures in the Crystal Mountain and Blakely Sandstones, both Ordovician, with mineralization dated to the Late Pennsylvanian to Early Permian. Act 128 of 1967 made quartz crystal the state mineral. The Quartz Page adds that the occasional faden specimens from these pockets show that the fissures opened gradually rather than all at once.
What is faden quartz associated with in tradition?
In crystal traditions, faden quartz is associated with connection and mending, an idea drawn directly from its visible mended seam. That symbolism is a reading of the geology, and the geology is the part that can be checked.
What to look for when you buy faden quartz
Hold the piece up to a window or a single bright light and find the thread before anything else. A good faden runs as a clear, continuous milky line, ideally from edge to edge, and the crystal around it is transparent enough to see it from both sides. Then check:
- Thread visibility. A faint or interrupted line is still a faden, but it should be visible in the listing photo, not only promised in the title.
- Terminations. Flat faden plates often have small terminations along both long edges. Count the chips; small plates from the main Pakistani source are inexpensive, so damage should be reflected in the price.
- Label honesty. "Tabby" alone is a shape. Ask whether the thread is present.
- Locality. Waziristan or "Pakistan" is the common answer; Arkansas and Alpine faden are less often offered.
From our stock:
- FADEN Tabby quartz: flat tabular crystals at an entry price; turn each one against the light to find the white thread crossing the plate.
- FADEN Tabby Quartz Specimens: small flat specimens of the same type, useful for comparing how thread width and clarity vary from piece to piece.
- Quartz Point Cluster from India: ordinary prismatic points to set beside a faden plate, so the difference between normal c-axis growth and the flattened faden habit is obvious in hand.
Digital Towns Market
Faden quartz in stock
Frequently asked questions
What does faden mean?
Faden is the German word for thread, pronounced roughly "fah-den". The English term faden quartz comes from the German Fadenquarz. It refers to the white, thread-like line visible inside the crystal, not to the crystal's shape.
Is faden quartz rare?
Faden quartz is uncommon compared with ordinary points, but it is not a rarity on the market, because Waziristan in Pakistan has produced large numbers of flat, clear faden crystals. Sharp, transparent examples with a strong, continuous thread from Arkansas or the Alps are much harder to find.
What is the difference between tabby and faden quartz?
Tabby describes shape: a flattened, tabular quartz crystal. Faden describes an internal feature: the resealed white thread. Many faden crystals are tabby, but some tabby crystals have no thread, and some faden crystals are not flat. Look for the thread itself.
Is the white line in faden quartz a crack?
It began as cracks, but it is now solid, regrown quartz. The line is a dense trail of tiny fluid and gas inclusions left by repeated breaking and mending. A faden crystal is as solid as any quartz crystal of the same quality and does not need special handling.
Can faden quartz be faked?
No convincing faden imitation is in wide circulation. The common problem is labeling: flat quartz without a visible thread sold as faden, or "faden" used loosely for any milky streak. Check the listing photos for a continuous line crossing the crystal.
Sources
- The Quartz Page (A. C. Akhavan), Growth Forms: Faden Quartz: http://www.quartzpage.de/gro_text.html
- The Quartz Page (A. C. Akhavan), Ouachita Mountains, Arkansas: http://www.quartzpage.de/ark.html
- The Quartz Page (A. C. Akhavan), Alpine-Type Fissures: http://www.quartzpage.de/atf.html
- New Mexico Bureau of Geology and Mineral Resources, Unusual quartz crystal growth habits (Jack Thompson, NM Mineral Symposium 2006): https://geoinfo.nmt.edu/museum/nmms/abstracts/view.cfm?aid=307
- Webmineral, Quartz Mineral Data: https://webmineral.com/data/Quartz.shtml
- Arkansas Geological Survey, Quartz (Industrial): https://geology.arkansas.gov/minerals/industrial/Quartz-%28Industrial%29.html