Is anatase magnetic?
No, as USGS measured it: one anatase sample, not pulled at 1.70 amp. Of 377 rows in its table, 144 were never pulled; 64, anatase included, on one sample.
No, on the one measurement there is. USGS Open-File Report 99-529 ran 1 anatase sample through a Frantz separator, and none of it was pulled at 1.70 amp, the maximum: diamagnetic by its definitions. The Handbook sheet for anatase, TiO2, hardness 5.5 to 6, prints no magnetic property. Of the table’s 377 rows, 64 share that one-sample, never-pulled footing.
In short
- Two sources, one sample. USGS Open-File Report 99-529 (Rosenblum and Brownfield) ran anatase through a Frantz isodynamic separator: total range above 1.70 amp, best above 1.70, 1 sample. The report calls diamagnetic the minerals that are nonmagnetic at 1.70 amps, the greatest current its separators reached. The Handbook of Mineralogy anatase sheet prints no magnetic property; its only magnet word is titanian magnetite, on the Association line.
- The one-sample shelf. A script parsing all 377 data rows of USGS Open-File Report 99-529, Table 1 finds 144 whose total range is written above 1.70 amp: never pulled at all. Of those 144, 64 rest on a single sample, 31 on two and 23 on three. Anatase is one of the 64, with datolite, benitoite and orpiment. The report says the data rest on 1 to 18 samples per species, and that more samples give better reliability.
- Same formula, other rows. Brookite, 2 samples, has a total range of 0.70 to above 1.70 amp; rutile, 10 samples, 0.80 to above 1.70. Both have a best range above 1.70. USGS says ranges running from 0.50 or 1.00 amp to above 1.70 probably involved some contamination, but does not say which samples. Anatase’s one sample showed no such tail.
- Documented failure: the colour rule. USGS writes that colorless or white minerals are generally diamagnetic and dark-colored, opaque minerals are generally pulled below 1.00 amp, naming red rutile, some corundum, microlite, cassiterite and many sulfides as exceptions. The anatase sheet’s colours include indigo and black, yet its one sample was not pulled. Colour is not a magnet test for TiO2.
- The decision. Not magnetic as USGS measured it, on one sample. A pull from an anatase specimen points at its company: the sheet names titanian magnetite, ilmenite and hematite among its associates, and those rows are set out on is ilmenite magnetic. The species facts are on anatase.
| Samples per row | Never-pulled rows | Share of the 144 | Examples (Table 1 names) |
|---|---|---|---|
| 1 | 64 | 44% | Anatase, Datolite, Benitoite, Howlite, Orpiment, Petalite, Proustite, Strontianite, Wavellite, Witherite |
| 2 | 31 | 22% | Andalusite, Aragonite, Colemanite, Kyanite, Natrolite, Pectolite, Sillimanite, Ulexite, Variscite |
| 3 | 23 | 16% | Corundum, Enargite, Lepidolite, Realgar, Smithsonite, Spodumene, Topaz |
| 4 | 13 | 9% | Cinnabar, Dolomite, Gypsum, Hemimorphite, Scheelite, Sodalite |
| 5 | 3 | 2% | Tetrahedrite, Zircon |
| 6 | 5 | 3% | Barite, Beryl, Cassiterite, Niccolite, Stibnite |
| 8 to 10 | 5 | 3% | Calcite (8); Galena, Pyrite (9); Quartz (10) |
| TiO2 rows, for comparison | 1 of 3 | — | Anatase above 1.70 (1 sample); Brookite 0.70 to above 1.70 (2); Rutile 0.80 to above 1.70 (10) |
Is anatase magnetic? What USGS measured
USGS did not pull anatase at 1.70 amp, the top of its separator. USGS Open-File Report 99-529 (Rosenblum and Brownfield) ran 1084 samples of 378 mineral species through Frantz isodynamic separators, on grains of 125 to 150 micrometres at a 15° side tilt. Anatase’s row: total range above 1.70 amp, best range above 1.70, 1 sample, no often-locked flag and no depends-on-chemistry note. The report defines diamagnetic minerals as nonmagnetic at 1.70 amps, paramagnetic as separable up to 1.70, and ferromagnetic as strongly attracted to a magnet, like a piece of iron.
How the top of the range was tested. For a colorless mineral suspected of being diamagnetic, the report says a first pass at 0.50 amp was followed by passes at 1.00 and at the highest setting, about 1.70; it does not say which procedure the anatase sample went through. It is concerned with practical separation, not with susceptibility in physical units. In that sense, and only that sense, this page answers no.
What the sheet says. The Handbook of Mineralogy anatase sheet gives TiO2, tetragonal, hardness 5.5 to 6, density 3.79 to 3.97, a white to pale yellow streak, and no magnetic property. The rutile and brookite sheets print none either. The site-wide summary is on which minerals are magnetic.
How firm is that? The one-sample shelf
Anatase’s no rests on one sample, and it shares that footing with 63 other rows. Method: a script parsed every data line of Table 1 into name, total range, best range and sample count, and kept the rows whose total range is written exactly above 1.70 amp. Result: 144 of 377 rows were never pulled. By sample count, 64 rest on 1, 31 on 2, 23 on 3, 13 on 4, 3 on 5, 5 on 6, and 5 on 8 to 10. Quartz, on 10, is the best-sampled; anatase, on 1, is among the least.
Why the count matters. The report’s first conclusion is that its data rest on 1 to 18 samples per species and that the greater the number of samples, the better the reliability. One anatase sample from one source is a result, not a range. Of the 151 Table 1 rows that rest on one sample, 64 are on this shelf.
Not the same as the other pages. The rows that pull earliest are counted on is pentlandite magnetic; the gap between hematite and magnetite is on is hematite magnetic; the titanium minerals in order of best range, and the split between ilmenite and the TiO2 rows, are on is ilmenite magnetic. None of their assets is repeated here.
Why did rutile and brookite pull and anatase not?
The table does not say, and neither does this page. All three are TiO2. Brookite’s 2 samples have a total range of 0.70 to above 1.70 amp; rutile’s 10 samples, 0.80 to above 1.70; both have a best range above 1.70, so most of each sample stayed behind. USGS says chemistry is the main factor controlling magnetic susceptibility, and that ranges from 0.50 or 1.00 amp to above 1.70 probably involved some contamination, which often could not be confirmed even under the microscope. It does not tie either remark to these rows.
What the sheets show. The anatase sheet’s two Brazilian analyses carry 0.10 and 1.11 wt% Fe2O3; the rutile sheet’s Graves Mountain analysis 2.62; the brookite sheet’s two analyses 1.41 and 1.48. Those are the sheets’ samples, not USGS’s, so they cannot explain the table. The rutile sheet also says rutile is black if high in Nb–Ta.
Documented failure: the colour rule. USGS writes that dark-colored and opaque minerals are generally extracted at less than 1.00 amp, and less commonly at greater amperages, naming red rutile, some corundum, microlite, cassiterite and many sulfides as exceptions. The anatase sheet lists indigo and black among its colours, yet its sample was not pulled. A dark TiO2 crystal that ignores a magnet is consistent with the record. The separations that do work are on anatase vs rutile.
How to read a magnet on an anatase specimen
A pull is information about the company, not the anatase. Neither source tests a hand magnet, so this is a reading of the records, not a test result. The anatase sheet’s Association line is brookite, rutile, titanite, ilmenite, titanian magnetite, hematite and quartz. Table 1 has no row for titanian magnetite; its magnetite row has a best range of 0.01 amp, ilmenite 0.20 to 0.30 and hematite 0.10 to 0.30. USGS warns that micro-inclusions of magnetite or other ferromagnetic minerals make the lower limit of extraction difficult or impossible to determine.
What to check instead. Anatase is the steep-pyramid TiO2, hardness 5.5 to 6, with a white to pale yellow streak; a 20.00 g piece reads 14.72 to 14.96 g in water. The method for the streak is on how to use a streak plate and for weight on how to measure specific gravity at home.
On the label. Write anatase when habit, streak and weight agree, whatever the magnet does. The magnetism questions are indexed at the collecting guides. Nothing on this site is offered for sale; the wanted list is the only commercial route.