How to tell if malachite is real
A malachite specimen has a density of 4.05, so a 20.00 g piece weighs 15.06 g in water; 3.6 is the floor. Then check the pale green streak. No acid test here.
To tell if malachite is real, weigh it first: the Handbook of Mineralogy gives a measured density of 4.05, and gem references put the floor at 3.6, so a clean 20.00 g piece must weigh at least 14.44 g suspended in water. Then check for a pale green streak, hardness 3.5 to 4, and banding with natural geometry. No acid test is given here.
In short
- Heft first, because it costs nothing. Malachite's measured density is 4.05. The International Gem Society says as low as 3.6 in admixtures or when fibrous, and geology.com gives 3.6 to 4.0. A 20.00 g piece weighs 15.06 g in water at 4.05 and at least 14.44 g at 3.6. Anything lighter is not solid malachite, whatever it is made of.
- The heft, streak and band rule. Of the 176 sheets in this site's reference set, 102 list green in the Color field. 43 of those reach a measured density of 3.6, 14 of the 43 have a streak described as green, and only malachite of the 14 also records banding.
- Heavy green minerals that are not malachite do exist. Brochantite, atacamite and pseudomalachite pass the heft and streak checks. A piece that passes everything except banding is real, but may be a different copper mineral.
- Treated is not fake. The International Gem Society says malachite rarely receives treatment, but lower-quality pieces may be stabilised with plastic resin or waxed. That is malachite with a disclosure.
- No acid test here. Reference texts list one; it is destructive, and it is a chemical-handling question this page does not advise on. Why acid matters to malachite at all is on why is my malachite dull.
| Step | Malachite gives | The number | Green sheets still in (of 102) | Real minerals that still pass |
|---|---|---|---|---|
| 1. Weigh in water (20.00 g piece) | 15.06 g | Density 4.05; floor 3.6 = 14.44 g | 43 reach 3.6 or more | Brochantite 3.97, atacamite 3.745 to 3.776, pseudomalachite 4.15 to 4.35, and 39 others |
| 2. Streak, hidden spot | Pale green | Streak field names green | 14 of the 43 | Antlerite, atacamite, brochantite, conichalcite, olivenite, paratacamite, pseudomalachite and 6 others |
| 3. Banding in the mass | Commonly banded in masses | Color field records banding | 1 of the 14: malachite | None in the set |
| 4. Steel point, hidden spot | Marked: hardness 3.5 to 4 | Steel is conventionally about 5.5 | Not used to count | 12 of the 14 print a hardness no higher than 4.5 |
| 5. Lens on the surface | Wax or plastic resin on some pieces (IGS) | - | - | Stabilised malachite is still malachite |
How to tell if malachite is real: the five checks, in order
Real malachite is heavy, soft, banded, and leaves a pale green streak. The Handbook of Mineralogy prints it as Cu2(CO3)(OH)2, hardness 3.5 to 4, measured density 4.05, streak pale green, colour bright green, dark green or blackish green, commonly banded in masses, and typically stalactitic, mammillary or botryoidal. The checks run from harmless to marking.
- Look (day one, no tools). The geology.com malachite article says sawn surfaces often show banding and eyes similar to agate, and that the better synthetics can usually be recognised because their banding and eyes do not have a natural geometry.
- Weigh it in water. A clean 20.00 g piece weighs 15.06 g at 4.05 and at least 14.44 g at the 3.6 floor. Weigh loose beads together, with any cord, clasp or metal removed first, because they change the result. The method is on how to measure specific gravity at home.
- Streak, on a hidden spot. A pale green line on unglazed porcelain; the technique is on how to use a streak plate. The International Gem Society calls streak and acid tests destructive and a last resort on finished pieces.
- Steel point, on a hidden spot. Malachite at 3.5 to 4 is marked. A green stone that steel will not mark is not malachite.
- Lens. Wax and resin sit in pores and voids. The International Gem Society says lower-quality, less compact pieces may be stabilised with plastic resins or given a wax polish.
The finish state: heavy, pale green streak, marked by steel, natural banding: consistent with malachite. Heavy with a green streak but no banding: a green copper mineral, and possibly malachite in crystals or crusts.
Is my malachite real? The heft, streak and band rule, counted
Of the 176 Handbook sheets in this site's reference set, malachite is the only one whose Color field names green and records banding, and which also reaches a measured density of 3.6 and has a green streak. Method: pdftotext -layout text; the Color and Streak fields cut out by regular expression and searched case-insensitively; the D(meas.) line read by script, including the older sheets' printed ranges.
- 102 of 176 list green in the Color field.
- 43 of the 102 reach a measured density of 3.6 or more. Of those 43, 30 print a Streak field.
- 14 of the 43 have a streak described with the word green: antlerite, atacamite, beudantite, brochantite, chloroxiphite, clinoclase, conichalcite, duftite, malachite, mottramite, olivenite, paratacamite, pseudomalachite and uraninite.
- 1 of the 14 records banding in its Color field: malachite. The one other green sheet that mentions banding there is hydrozincite, whose spherules may be concentrically color banded, and whose sheet prints no streak.
What the rule does not do. Banding is a habit of massive material. A malachite crystal spray, crystals to 9 cm on the sheet, will not show it. For crystals, the first two steps narrow the field to 14 names and the malachite species page takes over. Copper-mineral look-alikes are compared on brochantite and atacamite.
The 3.6 floor: weighing malachite beads and pieces
A clean 20.00 g malachite weighs 15.06 g in water at the sheet's 4.05, and 14.44 g at the 3.6 floor: a 0.62 g band. Worked: at 4.05 the volume is 20.00 divided by 4.05, 4.94 cm³, so the weight in water is 15.06 g. At 3.6 the volume is 5.56 cm³ and the weight 14.44 g. The floor is set by the sources, not by this site: the International Gem Society gives 4.05, as low as 3.6 in admixtures or when fibrous, and geology.com gives 3.6 to 4.0 and calls the density striking for a green mineral.
What this page does not claim. It quotes no density for resin, glass or other imitation materials, because none was verified at source. The test works without them: whatever a piece is made of, below 14.44 g for 20.00 g it is not compact malachite. The two sources also disagree about synthetics. Geology.com says synthetic malachite has been made and used for jewellery and small sculptures. The International Gem Society says malachite has been synthesised for research but is not found commercially. Both positions are reported here; neither is resolved.
Why this page gives no acid test
Malachite is a carbonate, and reference texts list an acid test for it; this page does not describe one. The International Gem Society lists effervesces in warm acids under identification and says the test is destructive. The heft, streak and band rule reaches the same finish state without a chemical. Hazard questions about malachite, including dust and working it, are on is malachite toxic and toxic minerals in a collection; this is not health or safety advice.
More identification guides are indexed at the collecting guides, and the species in the species index. Nothing here is offered for sale; the wanted list is the only commercial route.