What is MIME type "chemical/x-xyz"?

A MIME type is a string that tells browsers and other tools how to handle a particular kind of file.

chemical/x-xyz is a MIME type for files that hold chemical structure data. It marks text files that list atoms and their 3D positions. Each file starts with the number of atoms, followed by a comment line, then lines for each atom’s element and coordinates.
This format helps software read molecular geometries quickly.

Main use: Storing and sharing molecular structure information.
Visualization: Many chemistry tools display molecules using these files.
Simulation: They are used as input in computational chemistry programs.
Editing: Users can inspect and adjust simple molecular models.

This MIME type is tied to files with the extension XYZ. For more details on chemical file formats and usage, visit Filext.

Associated file extensions

.xyz

Usage Examples

HTTP Header

When serving content with this MIME type, set the Content-Type header:


    Content-Type: chemical/x-xyz

HTML

In HTML, you can specify the MIME type in various elements:


    <a href="file.dat" type="chemical/x-xyz">Download file</a>

Server-side (Node.js)

Setting the Content-Type header in Node.js:


    const http = require('http');    
    
    http.createServer((req, res) => {    
      res.setHeader('Content-Type', 'chemical/x-xyz');    
      res.end('Content here');    
    }).listen(3000);

Associated file extensions

.xyz

FAQs

What is the chemical/x-xyz MIME type used for?

The chemical/x-xyz MIME type is used to identify files containing Cartesian coordinates of atoms in a molecule. It tells software that the associated file (usually with a .xyz extension) contains plain text data describing molecular geometry, allowing chemistry applications to visualize or simulate the structure.

How do I open a file sent as chemical/x-xyz?

You typically need specialized scientific software such as Avogadro, Jmol, or VMD to visualize the 3D structure. However, because the underlying format is simple plain text, you can also open these files in any standard text editor (like Notepad or TextEdit) to inspect the raw coordinate data.

How do I configure Apache or Nginx to serve .xyz files correctly?

Since this is a non-standard type, you often need to add it manually. For Apache, add the line AddType chemical/x-xyz .xyz to your .htaccess or config file. For Nginx, add chemical/x-xyz xyz; inside your types { ... } block or mime.types file.

Can web browsers display chemical/x-xyz files natively?

No, standard web browsers like Chrome or Firefox cannot render 3D molecules natively. To display these files on a website, developers use JavaScript libraries such as 3Dmol.js or JSmol, which parse the chemical/x-xyz data and render interactive models within the browser.

Why does this MIME type start with 'x-'?

The x- prefix indicates that chemical/x-xyz is an experimental or private subtype that has not been officially registered with the IANA. While it is not a formal standard, it is widely recognized and supported by chemical informatics software and the scientific community.

What is the difference between chemical/x-xyz and chemical/x-pdb?

While both store molecular data, chemical/x-xyz is a very simple format containing primarily atom types and positions. In contrast, chemical/x-pdb (Protein Data Bank format) allows for much more complex metadata, including bonding information, secondary structures, and crystallographic data.

General FAQ

What is a MIME type?

A MIME (Multipurpose Internet Mail Extensions) type is a standard that indicates the nature and format of a document, file, or assortment of bytes. MIME types are defined and standardized in IETF's RFC 6838.

MIME types are important because they help browsers and servers understand how to process a file. When a browser receives a file from a server, it uses the MIME type to determine how to display or handle the content, whether it's an image to display, a PDF to open in a viewer, or a video to play.

MIME types consist of a type and a subtype, separated by a slash (e.g., text/html, image/jpeg, application/pdf). Some MIME types also include optional parameters.

How do I find the MIME type for a file?

You can check the file extension or use a file identification tool such as file --mime-type on the command line. Many programming languages also provide libraries to detect MIME types.

Why are multiple MIME types listed for one extension?

Different applications and historical conventions may use alternative MIME identifiers for the same kind of file. Showing them all helps ensure compatibility across systems.