silicates
Muscovite
KAl2(Si3Al)O10(OH)2
- Also known as
- micafuchsiteisinglassMuscovy glass
- Crystal system
- monoclinic
- Hardness
- 2–2.5 on the Mohs scale
- Lustre
- pearly
- Colour
- Colourless, silvery, pale brown, and green as fuchsite
- Where it forms
- In granites, pegmatites and metamorphic rocks. It is one of the commonest minerals in the crust and splits into sheets of almost molecular thinness.
- Chiefly from
- Jharkhand and Bihar, IndiaMadagascarBrazilNorth Carolina, United States
Why it is that colour
Pure muscovite is colourless and transparent in thin sheets. Chromium gives the green of fuchsite; iron gives brown tones.
Safety
Safe to handle. Mica dust is a respiratory hazard in mining and processing, and pneumoconiosis among mica workers is documented.
Where it comes from
This is the entry that matters. India supplies a large share of the world’s sheet and scrap mica, much of it from Jharkhand and Bihar, and investigations by Reuters, the Thomson Reuters Foundation, Terre des Hommes and others have repeatedly documented child labour in illegal mines there, together with deaths in collapses that go unreported because the mines are unlicensed. Madagascar’s mica sector has been documented as employing thousands of children. Mica reaches cosmetics, paint, electronics and car finishes, and the supply chains have been extremely difficult to trace.
Historical use
Used for stove and lantern windows before heat-resistant glass, for electrical insulation from the nineteenth century, and now overwhelmingly as a pigment additive that gives cosmetics and paint their shimmer.
Recorded as history and attributed where possible. That a stone was used for something establishes that people used it, not that it worked.
What is attributed to it, and since when
No traditional symbolic use of note. The name comes from Muscovy glass — sheets of muscovite were used as window panes in Russia. Modern meanings are recent.
Described, not endorsed. Dating a claim is not the same as assessing it — but an association that first appears in a book published in 1985 is not an ancient inheritance, whatever the label says. A sincere account of feeling better is compatible with the stone doing nothing — see the placebo effect.
Worth knowing
Mica is the strongest single argument in this collection for taking sourcing seriously, and it is mostly invisible because most mica is not sold as a stone. It is the shimmer in eyeshadow, the pearl in car paint, the glitter in nail varnish and the insulation in electrical goods.
The investigations are not ambiguous. Reporting from Jharkhand and Bihar since 2016 has documented children working in illegal mines, fatal collapses recorded as something else or not recorded at all, and a chain from those pits through local traders to international processors that is difficult to audit and easy not to look at. Madagascar has a parallel problem, documented by Terre des Hommes in 2019.
A person choosing a crystal on ethical grounds is usually thinking about the crystal. The mineral most likely to have cost a child something is the one in their make-up.
Identity checked against IMA-CNMNC master list, June 2025.