Identification · 10 min
A repeatable identification routine
Tests in the right order eliminate the most candidates for the least effort, and stop you damaging the specimen to learn something you did not need.
Guides
Collecting · 10 min
Buying your first specimens without wasting money
The early mistakes are predictable: paying for size, ignoring locality, and buying treated material without knowing it.
Collecting · 8 min
Cataloguing: the part collectors skip and later regret
A specimen and its label are one object. Separate them and you have destroyed most of what made it worth keeping.
Technique · 10 min
Cleaning specimens without destroying them
Most damage to mineral specimens happens after collection, during enthusiastic cleaning.
Identification · 8 min
Cleavage and fracture: how a mineral chooses to break
Cleavage follows planes of weak bonding and is diagnostic. Fracture is what happens when there are none.
Reference · 10 min
The seven crystal systems, in plain terms
Every crystalline mineral belongs to one of seven systems, defined by the symmetry of its unit cell rather than by the shape of any particular specimen.
Collecting · 11 min
Fakes, composites and treatments worth recognising
Most deception in mineral dealing is not a forged specimen. It is a real specimen improved, assembled or relabelled.
Collecting · 10 min
Field collecting: permission, safety and what to leave
Access is a legal question before it is a practical one, and the answer differs by land ownership, country and site.
Technique · 8 min
Fluorescent minerals and why the lamp matters
Fluorescence is spectacular, unreliable as an identification test, and highly dependent on which ultraviolet wavelength you use.
Reference · 9 min
Levinson suffixes: why so many species end in brackets
Names like monazite-(Ce) and xenotime-(Y) look like variants. They are separate species, and the bracket is doing real work.
Identification · 9 min
The Mohs scale, and the four things it will not tell you
Hardness is the most useful field test there is, and the most frequently over-read. It is ordinal, directional, and says nothing about toughness.
Reference · 8 min
How to read a Nickel-Strunz code
A code like 9.AG.20 is not an accession number. Every segment narrows the chemistry, and reading it saves looking things up.
Reference · 8 min
Pseudomorphs: the shape of one mineral, the substance of another
When a mineral is replaced but keeps its predecessor outline, identification by shape fails completely.
Identification · 9 min
Quartz varieties: one species, a dozen trade names
Amethyst, citrine, agate and jasper are all quartz. The variety names describe colour and texture, not composition.
Identification · 9 min
How to read a mineral formula without a chemistry degree
Subscripts, brackets, dots and superscripts each mean one specific thing. Once you know the five conventions, most formulas become readable.
Technique · 8 min
Measuring specific gravity with a kitchen scale
Density separates minerals that every other field test confuses. You need a scale, a cup of water and some thread.
Collecting · 8 min
Storage: what light, air and dust actually do
Some minerals fade, some dehydrate, and a few dissolve in the moisture of an ordinary room. Display is not neutral.
Identification · 7 min
Streak testing: the cheapest reliable test you own
Body colour lies constantly. Streak colour is far more stable, and a porcelain tile costs almost nothing.
Reference · 8 min
Twinning, and why some crystals look impossible
Twinned crystals appear to break symmetry rules. They do not — they are two orientations of the same structure sharing a boundary.
Reference · 8 min
Locality data: what a good label records
Locality is the difference between a specimen and a rock. Recording it well takes a minute and lasts a century.