Malachite
On the label: Malachite · Gemstone
What it is
Banded green copper carbonate, Mohs 3.5 to 4: soft, scratches easily, and its dust is toxic, so keep it off cut skin and away from acids and water.
Gemstones: Natural gemstones, as mined and cut. Hardness (Mohs scale) says what scratches what; treatment (heat, oil, dye) must be disclosed under FTC rules.
Wikidata: Carbonate mineral. Q164411 →
In the research
86 PubMed papers mention it with jewelry, allergy, eyewear or UV; the three most recent:
- Revisiting Carbon Quantum Dots for Malachite Green: Mechanistic Insights, Functional Integration, and Translational Barriers · Luminescence : the journal of biological and chemical luminescence, 2026
- Molecular structure dependent convective control in binary solvents: a femtosecond thermal lens study · Physical chemistry chemical physics : PCCP, 2026
- Hydrothermal-ultrasonication-assisted synthesis of visible-light activated NiO/CuO heterojunction for the photocatalytic degradation of organic pollutants · RSC advances, 2026
A paper is a paper, not a verdict: titles are listed so you can read them, and a study on one fabric or one filter says little about the piece in your hand.
Other gemstones
Clasp & Lens describes materials from the public record and does not appraise, grade or test pieces; what a listing states is the supplier's statement. If a piece causes a rash, take it off; a reaction that spreads or blisters is a doctor's question, and sunglasses are no substitute for impact-rated eye protection where that is required.