Collecting
Practical guidance on buying, grading, cleaning and storing mineral specimens, and on the labels, provenance and condition questions that are worth asking.
Practical guidance for buying and keeping specimens. Thumbnails fit a box of about 2.5 cm, miniatures run 3-5 cm and cabinet pieces 8-13 cm. Most British material is 100 years old or more, so labels carry provenance and disclosed restoration is normal. Cleavage, not hardness, is what breaks a specimen in storage.
Specimen sizes, and what the trade terms mean
Thumbnail, miniature, cabinet: the size categories are dealer conventions rather than standards. Knowing the ranges stop…
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Buying old collection material
Nearly all classic British material is old, and that makes the label part of the value and restoration a normal question…
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Handling and storing specimens
Most damage to a collection happens in a drawer, not out in the field. What actually threatens specimens — humidity, lig…
Read →What a fluorite specimen is worth
Locality, condition, crystal quality, colour and provenance, in roughly that order. Why no dealer can price fluorite by …
Read →How to identify a mineral specimen
Six tests you can run on a desk, in the order that eliminates the most possibilities fastest: habit, hardness, streak, c…
Read →Where to buy mineral specimens
Dealers, shows, auctions and online marketplaces each solve a different problem. What each one is good at, what it costs…
Read →Is my rock worth anything?
Usually not, and that is not a brush-off. What separates a specimen with real value from a heavy stone, and how to check…
Read →How to clean a mineral specimen
Water and a soft brush handle most of it. Quartz will tolerate almost anything and a soft arsenate crystal will not, and…
Read →Toxic minerals in a collection
Lead, arsenic, mercury, asbestiform fibres and uranium — what is genuinely dangerous on a shelf, what is not, and the on…
Read →Fluorescent minerals
Why some minerals glow, why the lamp matters far more than the rock does, why shortwave at 254 nm will burn your eyes, a…
Read →Why is my pyrite crumbling?
Pyrite decay is a chemical reaction, not a disease. Above 60% relative humidity a pyrite specimen oxidises to sulphates …
Read →Which minerals fade in light
Realgar, amethyst, green fluorite and the ruby silvers change irreversibly on a lit shelf. Which species are at risk, an…
Read →How to tell if a mineral specimen is repaired
Repair is normal in the mineral trade and undisclosed repair is not. A six-step inspection order, what raking light and …
Read →Is it legal to collect minerals in the UK?
Access is not permission and permission is not consent. Who owns the minerals, what a landowner can grant, and where the…
Read →Smithsonite vs hemimorphite
Two blue-green botryoidal zinc minerals from the same oxidised zones. Density separates them, acid settles it, hardness …
Read →What ex coll. means on a mineral label
Ex coll. is short for ex collectione, from the collection of. The abbreviations old labels use, and the three-part test …
Read →How to pack and ship mineral specimens
Double-box, 25 mm of soft padding on every face, and a gap that compresses. The packing order that survives a courier, a…
Read →How to tell if a crystal is fake or treated
Lab-grown chalcanthite, dyed howlite, aura quartz and glued clusters. What is manufactured, what is disclosed treatment,…
Read →“I inherited a mineral collection” — what to do first
Do nothing irreversible for 30 days. Photograph every specimen with its label, keep labels with their stones, and check …
Read →Is my mineral radioactive?
Fewer than 300 species carry uranium or thorium, and a label names most of them. Dust and radon matter more than direct …
Read →Why is my specimen growing a white crust?
Four different faults produce a pale crust, and the humidity causing each is different. Below 35% dehydration, above 60%…
Read →How to tell pyromorphite from mimetite
Both are hardness 3.5 to 4 and their densities differ by only 0.20. No hand test separates them, because they form a con…
Read →What is a type locality?
The locality a species was first described from, and where its type material was collected. Not the best locality, the o…
Read →Do I need a UV lamp for mineral collecting?
Mostly no. Longwave at 365 nm shows the least. Shortwave at 254 nm shows the most and needs eye protection. What each ba…
Read →What to look for when buying minerals online
Read the photographs before the description, and check the locality on the label. A UK dealer owes you 14 days to cancel…
Read →Is it safe to collect on old mine dumps?
Ground hazards hurt collectors long before the chemistry does. Never enter a shaft or adit on an old orefield, and get p…
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