Pegmatite
Pegmatite is igneous (intrusive, very coarse). In the hand, it rates 6 to 7 (aggregate) on the Mohs scale, and it runs white-pink-gray with huge mineral patches and mica-spangled. Granite gone giant, individual feldspar, quartz, and mica crystals measured in centimeters to meters, often hosting gem pockets.
The geology.
Pegmatite carries the formula . It belongs to the, system. The trade files it under igneous (intrusive, very coarse).
It sits at 6 to 7 (aggregate) on the Mohs scale. The surface reads vitreous, coarse sparkle. Light behaviour is opaque with glassy crystal patches. Specific gravity runs 2.6 to 2.7. The streak is,. It breaks with breaks along giant crystal boundaries.
Granite gone giant, individual feldspar, quartz, and mica crystals measured in centimeters to meters, often hosting gem pockets.
Common cuts are rough chunks with book mica, graphic granite slabs or gem-pocket specimens.
The origins.
Late-stage granite fluids worldwide: Brazil, Pakistan, Madagascar, Maine and California (USA), the source rock of most gem tourmaline, beryl, and kunzite.
On value, the database notes: common as rock; gem-pocket specimens carry the value.
Traditional associations.
In energy work traditions, pegmatite has little lore of its own, it is the mother rock that births the gems with the lore.
Included for completeness. Tradition is worth knowing about, and it is worth keeping separate from the mineralogy.
Spotting the real thing.
Granite gone giant, individual feldspar, quartz, and mica crystals measured in centimeters to meters, often hosting gem pockets.
| Looks like | How to tell them apart |
|---|---|
| Granite | Same minerals; pegmatite's grains are dramatically larger (thumb-sized and up) |
| Gneiss | Gneiss is banded; pegmatite is randomly gigantic |
| Quartz vein | Veins are quartz alone; pegmatite mixes giant feldspar and mica too |
At-home tests.
These checks cost nothing. Daylight, a 10x loupe and a little patience are the whole kit for pegmatite.
| Test | What you should see |
|---|---|
| By eye | Crystals visible from across the room |
| By eye | Book mica and blocky feldspar chunks |
| Scratch check | Scratches glass (quartz portions) |
Destructive tests belong to a gemologist, not a kitchen table. If a piece matters to you, pay for an appraisal before you take a file to it.
Care & handling.
At 6 to 7 (aggregate) on the Mohs scale it handles careful wear but scratches against quartz and dust. Store it separately and take rings off before rough work.
It breaks with breaks along giant crystal boundaries, which is worth knowing before you set it or drop it.
Clean it by hand, dry it properly, and keep it away from ultrasonic cleaners and hot steam.
A deeper look.
Extended detail on composition, sourcing, authentication and market value.
The physical record
The formula on record is . Crystal system:,. Specific gravity: 2.6 to 2.7. Streak:,. Cleavage and fracture: Breaks along giant crystal boundaries.
How it reaches the market
Late-stage granite fluids worldwide: Brazil, Pakistan, Madagascar, Maine and California (USA), the source rock of most gem tourmaline, beryl, and kunzite.
What it gets confused with
Granite: Same minerals; pegmatite's grains are dramatically larger (thumb-sized and up). Gneiss: Gneiss is banded; pegmatite is randomly gigantic. Quartz vein: Veins are quartz alone; pegmatite mixes giant feldspar and mica too.
What it is worth
Common as rock; gem-pocket specimens carry the value.
One more thing
Pegmatites grew crystals meters long in mere days to years, water-rich magma soup is geology's fast-forward button.
An education-first guide.
We do not stock pegmatite. Writing it up regardless is the point of a reference library.
Explore the Crystal Guide