Astimex Microanalysis Standards

Astimex Standards Ltd. produces polished metallic element, rare earth element, rare earth phosphate, mineral and synthetic compound standards suitable for Electron Microprobe and Scanning Electron Microscope X-ray Analysis. They are also suitable for Laser Ablation Mass Spectrometric Analysis. Among our "Package mounts" (or standards for microanalysis), all naturally occurring stable elements are represented, with the exception of the noble gases. The pure metals are all of those which are stable and solid at room temperature and which can be prepared in a polished form. Some of them are more suitable than others for this type of use, and some degree of oxidation or failure to polish well may be expected in certain cases. The purity of the metals is always better than 99%, and most of them more than 99.99%. Details of the individual purities and source supplier are given with each purchase, or on request. Even the light element range, difficult to access by X-ray analysis is given complete coverage.

The 53 minerals and compounds, for which analyses are provided on purchase, are chosen to give comprehensive coverage of the elements, especially those which cannot be mounted in the pure form. These minerals are carefully selected on the basis of their homogeneity within and between grains, and have been analyzed quantitatively at the Universities of Toronto or Alberta. Some of the materials are synthetic and, after experimental confirmation that they contain no detectable impurities, ideal compositions have been assigned to them. Between the minerals and metals, most naturally occurring elements are represented in major concentrations, with the only notable exception being the noble gases. Metals and minerals can be mounted and polished separately or together, though there are certain recommended groupings, referred to below as Package Mounts, which are held as stock items, and for which the prices are set. However customers are encouraged to select the mount geometry and standard materials for their own individual needs, and custom arrangements will be quoted on request. It may be necessary to make substitutions from time to time in the minerals offered, but every effort will be made to preserve a similar diversity of range.

Labels, including a reference number and, in most cases, a description in letters 60 m high, are engraved onto the mounting medium using a computer controlled electron beam. This feature has proved extremely useful in route finding on the higher density mounts, particularly when the sample can only be observed through high power magnification. Carbon coating is necessary prior to the labelling operation. The lettering can be read in the secondary or backscattered electron images of an SEM or through the light microscope viewing system of a microprobe. Labels are normally written for direct viewing, but mirror images can be supplied on special order at no additional charge.

Electron beam lettering for albite

The popular mount sizes are 25mm diameter (1 inch) and 12.5mm ( inch). The 25mm mounts are stainless steel discs, 6mm thick; the 12.5mm mounts are also stainless steel but only 4mm thick. See the various layout patterns and contents of the Package Mounts. The Rare Earth Elements are grouped together in a single mount as this is convenient for geochemical work, and as several of these are unstable in the metallic form, fluorides are used as an alternate. The mounting medium used in all mounts is epoxy resin. Carbon coating is provided to give conductivity from the metal or mineral grains to the stainless steel mount which encloses the plastic.

The metals and minerals are most economically purchased in the Package Mounts, but in the case that a special selection of items is made, the charge is on a per item basis. Minerals and synthetic materials other than those listed may be available on request.

A Faraday cup, for accurate specimen current measurement, can be included in any of our standards mounts, occupying the vacant central position. The Faraday Cup consists of a 200 m platinum aperture flush with the mount surface and set in the top of a hollow stainless steel tube. The bottom of the tube is closed, and an electrical connection is made through the mount body.

Minerals and materials not listed above may be obtained on request, and a customer's own items can be included or substituted as a special order.