# Diogenite - Page: https://taslar.bumba.tr/en/stones/diogenite/ - Turkish: Diyojenit - Also known as: HED meteorite (diogenite) - Kind: Meteorite - Classification: Meteorites and impact stones › Stony meteorites - Hardness (Mohs): 5–6 - Specific gravity: 3.09–3.43 g/cm³ - Lustre: Dull - Transparency: Opaque - Colours: black (fusion crust), light-coloured (interior) - Composition: Mainly magnesium-rich orthopyroxene, with a little plagioclase and olivine. - Texture: A coarse-crystalline (plutonic) igneous rock that cooled slowly at depth; its crystals are larger than those of eucrites. - Value ladder: 6/9 step, Fine ornamental and collector stone A stone from deep inside asteroid Vesta: a rare achondrite of large, slowly cooled pyroxene crystals. Diogenites are achondrites of the HED meteorite clan, that is, stony meteorites without chondrules that melted and solidified again. They are thought to come from deep in the crust of the large asteroid 4 Vesta, between Mars and Jupiter. Having cooled slowly at depth, they have larger crystals than eucrites and are made mainly of magnesium-rich orthopyroxene. About 40 distinct diogenites are known. ## How does it form? Vesta melted and separated into layers at the start of the Solar System: a metal core in the middle, a mantle above it and a crust on the outside. Diogenites formed in the deep parts of this crust, where magma slowly cooled and solidified. Slow cooling gave crystals time to grow, so diogenites are coarser-grained than eucrites, which come from higher in the crust. Impacts on Vesta blasted these rocks into space. The fragments moved onto Earth-crossing paths and in time fell to Earth. ## What is it used for? - **Inside Vesta:** Diogenites are samples of the deep parts of Vesta's crust. - **Planet formation:** They help us understand how small planets that melted and separated into layers formed. - **The HED clan:** With eucrites and howardites, they are among the rare cases where meteorites that fall to Earth can be tied to a particular asteroid. ## Famous diogenites Johnstown (Colorado, 1924) is one of the best-known diogenite falls: the meteorite fell during a funeral, and several large pieces were recovered. ## How to recognise it - A black fusion crust outside; light-coloured inside. - Large pyroxene crystals can be seen by eye; there are no chondrules. - Only laboratory analysis can show that a stone is a diogenite and comes from Vesta. ## What determines its value? Diogenites are rare meteorites: only about 40 distinct specimens are known. Coming from a well-known asteroid like Vesta makes them valuable for both science and collecting. A piece's value depends on its mass, freshness, whether its crystals show and its documented origin. This information is educational, not buying, selling or investment advice. Value varies enormously with quality and treatment. ## Myths and misconceptions - Myth: The idea that meteorites come from the sky is a modern scientific discovery. Fact: The idea is very old: the ancient Greek philosopher Diogenes of Apollonia was among the first to suggest that meteorites come from space, which is why diogenites bear his name. The scientific world accepted it firmly only in 1803. ## Curious questions **How do we know diogenites come from Vesta?** Diogenites, together with eucrites and howardites, make up the HED clan. The composition of these meteorites matches Vesta's spectrum. The coarse crystals of diogenites show that magma cooled slowly in the deep parts of Vesta's crust. ## Did you know? - They are named after the ancient Greek philosopher Diogenes of Apollonia, the first to suggest that meteorites come from outer space. - The Johnstown meteorite, which fell in Colorado in 1924, came down during an outdoor funeral attended by more than 200 people, who saw or heard the stones fall. - One 23.5-kilogram piece of Johnstown buried itself 1.7 metres deep. ## Where is it found? - Johnstown (former Elwell), Colorado, USA (Known locality): An achondrite that fell on the afternoon of 6 July 1924 during an outdoor funeral attended by more than 200 people; one 23.5 kg piece buried itself 1.7 m deep. ## Sources - [Diogenite](https://en.wikipedia.org/wiki/Diogenite), Wikipedia - [Johnstown, Colorado](https://en.wikipedia.org/wiki/Johnstown,_Colorado), Wikipedia - [Meteorite porosities and densities: a review of trends in the data (D. T. Britt & G. J. Consolmagno), Lunar and Planetary Science XXXV, abstract 2108](https://www.lpi.usra.edu/meetings/lpsc2004/pdf/2108.pdf), Lunar and Planetary Institute, 2004 - [Handbook of Mineralogy: Enstatite](https://www.handbookofmineralogy.org/pdfs/enstatite.pdf), Mineralogical Society of America Source: https://taslar.bumba.tr/en/stones/diogenite/ · Licence: CC BY-SA 4.0