Aspirin

Chemical formula: C<sub>9</sub>H<sub>8</sub>O<sub>4</sub>

Aspirin (acetylsalicylic acid) is an organic chemical compound that can form colorless, needle-like crystals under laboratory conditions.

## Characteristics Aspirin, chemically known as acetylsalicylic acid, is a synthetic organic compound, not a mineral. It does not occur naturally and is not classified by the International Mineralogical Association (IMA). Under controlled crystallization conditions, for example, during slow evaporation of a solvent, it can form well-developed, colorless crystals. These typically take the form of elongated needles or thin, flattened tablets, often combining into radial or chaotic aggregates. ## Physical Properties Aspirin crystals are brittle and characterized by relatively low hardness. They exhibit a vitreous to pearly luster on the flat surfaces of the crystals. They are lightweight, with a density slightly greater than water (approximately 1.4 g/cm³). Due to their organic nature, they have a low melting point, around 136°C. ## History and Name The name "Aspirin" was registered as a trademark by the Bayer company in 1899. The name comes from "A" for the acetyl group, "spir" from spiraeic acid (an old name for salicylic acid, obtained from plants of the genus *Spiraea*), and the suffix "-in", commonly used in drug names. Acetylsalicylic acid was first synthesized in a pure and stable form by chemist Felix Hoffmann in 1897. ## Uses As a crystalline substance, aspirin has no industrial or collecting applications in crystal form. Its sole and primary use is as an active pharmaceutical ingredient, where it is widely used as an analgesic, anti-inflammatory, and antipyretic drug.

Properties

Mohs hardness
1-2
Luster
Vitreous
Streak
White
Density
1.4
Cleavage
Perfect on {001}
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Aspirin crystals can be identified by their characteristic needle-like or thin-tabular shape and colorless appearance. A key diagnostic feature is their low melting point and reaction to moisture – in humid air, they gradually begin to emit a vinegar smell. They are very soft and brittle. ## Distinguishing from Similar Substances Due to its synthetic origin, it is not confused with minerals in collecting practice. Under laboratory conditions, its needle-like crystals may resemble some naturally occurring sulfates or borates (e.g., gypsum, colemanite), but they differ completely in physical and chemical properties (solubility, hardness, reaction to heat). ## Crystal Forms It crystallizes in the monoclinic system. Most often, it forms elongated, needle-like crystals or thin, flattened plates. These crystals often form fan-shaped, radial, or haphazardly entangled aggregates.

Geological environment

## Genesis Aspirin is an exclusively synthetic product, obtained by the esterification of salicylic acid with acetic anhydride. It does not form in any natural geological processes and does not occur in nature. Its crystals are formed by crystallization from a supersaturated solution under laboratory or industrial conditions. ## Mineral Associations As a synthetic substance, it does not form natural associations with minerals. ## Localities No natural localities. It exists exclusively as a man-made product in laboratories and pharmaceutical factories worldwide.

Rarity

Synthetic substance

For collectors

## Quality Criteria Aspirin crystals are not an item of collector's trade. Any potential "collector's" specimens originate from laboratory syntheses, and their attractiveness is purely subjective and depends on the size, clarity, and aesthetics of the formed crystals or aggregates. There are no formal criteria for assessing their quality.

Care and storage

## Cleaning Aspirin crystals are soluble in water (especially hot water) and alcohols (ethanol, isopropanol). They should not be cleaned wet. Only gentle dust removal with a soft brush or compressed air from a safe distance is permissible. ## What to Avoid Absolute avoidance of contact with water, water vapor, and all organic solvents is necessary. Aspirin is sensitive to moisture, under the influence of which it hydrolyzes back to salicylic acid and acetic acid, which manifests as a characteristic vinegar smell. Elevated temperatures should be avoided, as it has a low melting point (136°C). ## Storage Specimens should be stored in a tightly sealed, dry container, away from heat sources and light. It is best to use a bag or box with a desiccant (e.g., silica gel) to prevent hydrolysis.

External references

Sources

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