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Photographic gallery.  Thousands of particles under the microscope.

Transpartent Isotropic Particles

This is part of a guide to the identification of particles seen in samples of free particles. It is designed to allow access to files using any significant feature noticed by the microscopist rather than requiring a specific set of measured parameters. Often the most significant feature of a particle is unique to that particle type and so is not a useful diagnostic element for a broader Key for particles in general. This guide will lead to the same particle through a number of different paths depending on features and the order of significance placed on those features by the microscopist/analyst. When a particle is found that appears to be similar to the one being identified it may be useful to go to the file of particles of that type. For instance, if it looks like a starch grain then it may be useful to go to the "Starch" file in this gallery and see a larger variety of starch grains for comparison. The photographs of the particles shown here are both from standard sets and from environmental samples collected over many years by this laboratory.

This file includes transparent isotropic particles of any shape.

Cubic Crystal System

These are isotropic particles that are in fact crystalline but belong to the cubic crystal system.

Salt From a Sawmill Garnet Crystal Sodium Chloride Marine Aerosol Diamond Abrasive

Spherical Structure

These may be colorless to any color. They tend to be a form of glass, inorganic or plastic, formed from the melt. The presence of gas bubbles often has significance with regard to the original substance that had been melted.

Flyash Flyash Fungal Spores


These particles may be any color and may show interference colors as in the case of some cosmetic particles. They may have accessory structures as in the case of fragments of insects. Skin flakes may appear isotropic because they have very low birefringence and are rather thin.

Insect Wing Insect Wing Insect Fragment Insect Fragment Cosmetics Cosmetics Skin Flakes


Fibers are diffined here as structures with essentually parallel sides that are at least five times as long as they are wide. These fibers tend to be either organic or inorganic glasses though some plant phytoliths are in this category.

Glass Fiber from Pink Blanket Insulation Glass Fiber from Yellow Blanket Insulation Mineral Wool 100X 1 Glass Fiber, HVAC System Gypsum Board Glass Fiber Glass Fiber Look-A-Like Phytolith Cladophoria 800X (zoom) Diatom 125-3 Gillionella Fungal Hyphae Fungal Hyphae

Irregular Shape

These particles tend to be glasses, slags, or crystals of the cubic crystal system that lack any cleave plane, garnet for example.

Blast Furnace Slag Abrasive Pumice Abrasive

Diamond Abrasive

Garnet Garnet Garnet Garnet Garnet Garnet Garnet

Garnet Abrasive Garnet Abrasive