How to Catalogue a Personal Collection (Part 2)

In the last post about the NG Collection, I described how an Excel spreadsheet can be used for museum documentation. The next important step in cataloguing a personal collection is to decide on a numbering system and assign accession numbers to objects.

I decided to accession my collected rocks, minerals and fossils first since I know a lot of information about where they were collected, their age, what formation they came from, etc.; it was very important to me to get these vital pieces of information recorded first. The accession number for these objects is Cxxxx, where ‘C’ indicates that the object was collected by me and ‘xxxx’ is a four digit number. Due to the nature of Excel, sorting numbers in ascending order places C12 before C2. By adding leading zeroes (C0012 and C0002), accession numbers can be sorted in the correct order.

C0001 (2).jpg

C0001, beach pebbles from Sussex, England (author’s image)

I’ve accessioned my collected objects in chronological order so when two accession numbers are compared, I know whether one object was collected before the other. The pebbles in the picture above were collected 18 years ago and were the first to be accessioned.

I then had to think of a numbering system for objects that were purchased or donated to me. I initially wanted to number my minerals by using a simplified version of the system used by UCL’s Geology Collections, which is based on the Nickel-Strunz Classification. For example, copper is numbered as 1:3(x) where ‘x’ is a random number.


Mineral classification (image from


Pyrite (small gold cubes), galena (grey cubes) and fluorite (white cubes), LDUCG 2:4(30), from UCL’s Geology Collections (author’s image)

However, problems can arise when using this system. It’s very common for specimens to contain more than one mineral type. The specimen above contains three different minerals so there are three possible accession numbers: 2:4(x) for galena, 2:16(x) for pyrite or 4:1c(x) for halite – it was given a number corresponding to galena. Another issue is that accession numbers need to be changed if mineral classifications are updated. I came across some specimens of prehnite numbered as 8G:1(x) which indicates they were accessioned as ‘silicates of an unknown structure’. However, I later found other prehnite specimens numbered as 8B:8b(x) which indicates they are phyllosilicates. The first batch of prehnite specimens were accessioned at a time when the structure of prehnite was unknown and their accession numbers hadn’t been updated to reflect this new discovery. Using this kind of system means it’s likely that accession numbers will have to be changed at some point which is not ideal.

The issues with ‘meaningful’ accession numbers and alternative numbering systems were discussed on Twitter and after some great feedback, I managed to settle on a system. The purchased/donated minerals in my collection will be Mxxxx, the rocks Rxxxx and the fossils Fxxxx. These objects will not be accessioned in chronological order, partly because I do not know the exact date of when I obtained some of them.

I’ve recently acquired a new batch of rocks, minerals and fossils so I really need to get started on accessioning the rest of the objects in my collection!


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