The term framboid describes a micromorphological feature common to certain sedimentary minerals, particularly pyrite (FeS2). The first known use of the term is ascribed to Rust in 1935 and is derived from the French ‘la framboise’, meaning ‘raspberry’, reflecting the appearance of the structure under magnification.
Framboidal structure comprises roughly spherical aggregates of discrete equi-regular euhedral microcrystallites of around 0.5 μm in diameter, with the average aggregate size ranging from 5-20 μm. Framboid diameter tends to correlate positively with microcrystal size, and microcrystal packing is most commonly irregular and disordered. Framboids were once thought to be a fossilised bacterial colonies or microorganisms, but successful synthesis of this structure under laboratory conditions and observation of framboids in locations hostile to microbial life have discounted this theory.
Framboidal pyrite is commonly found in coastal sediments, for instance marsh soils, marine and estuarine sediments, and beach sands. It can also be observed in coal as well as magmatic and carbonate rocks. Other minerals known to exhibit framboidal structures include magnetite, hematite, and greigite. Greigite is considered an essential precursor of framboidal pyrite formation.
![]() |
This article about a specific mineral or mineraloid is a stub. You can help Wikipedia by expanding it. |
None of the audio/visual content is hosted on this site. All media is embedded from other sites such as GoogleVideo, Wikipedia, YouTube etc. Therefore, this site has no control over the copyright issues of the streaming media.
All issues concerning copyright violations should be aimed at the sites hosting the material. This site does not host any of the streaming media and the owner has not uploaded any of the material to the video hosting servers. Anyone can find the same content on Google Video or YouTube by themselves.
The owner of this site cannot know which documentaries are in public domain, which has been uploaded to e.g. YouTube by the owner and which has been uploaded without permission. The copyright owner must contact the source if he wants his material off the Internet completely.