Jaroslaw Majka’s Post

Our new paper “Neotypification of the name Centaurea crassifolia Bertol. (Asteraceae)” has just been published in Adansonia https://lnkd.in/d4qrHWbf

Natural Peridot Peridot contains inclusions of biotite flacks, water-lily leaves or lily pads , which are discs like decrepitation haloes frequently with small chromite crystal at the center, and small fluid drops, and gas bubbles.(Dictionary of Gems & Gemology - M Manutchehr - Danai)

Ampulex compressa In Sri Lanka, two metallic blue species of the genus Ampulex are found: Ampulex dissector and A. compressa (Fabricius). These species can be easily differentiated from one another. Specifically, Ampulex dissector is characterized by its light red hind femora, while A. compressa features light red mid and hind femora. Additionally, if the submarginal cells are visible, they can also aid in distinguishing between the two species.

My latest article in Lithos on some interesting peridotite xenoliths from the Fish River in the remote Southern Alps of New Zealand. 🌋 🐟 "A new set of ultra-refractory peridotite xenoliths contain abundant veins comprising phlogopite, amphibole and clinopyroxene. Melt models indicate that vein partial melting could generate geochemical aspects of the intraplate magmas." https://lnkd.in/g5MDWN8W

Well I would say that this is Thin Section Thursday, but it is more like Forgetful Friday, pardon me; I'm sure we have all been there. Anyhow the image today is the last of those from the Mendips. Here we see the quartz being overgrown by poikilotopic calcite, initially ferroan, later non-ferroan. These imply precipitation in reducing and then more oxic conditions, and suggest a burial origin (at least for the ferroan), possibly associated with the late stages of the quartz diagenesis that is considered hypogenic. But, that is not quite the end of the story; note the etching, particularly of the calcite crystals. The likely cause of this (courtesy of Peter Smart) is that the samples, retrieved from the infill of a cave system, represent a hypogene karst that was then overprinted by an epigene system in which a variety of mammal remains were recovered, including a notably fauna of hyenas, which are thought to have been responsible for bringing the other detritus into their den. This included some human teeth of neolithic age (poor them). Dissolution of the calcitic sediment on the cave floor could therefore be interpreted as a consequence of late-stage etching by hyena urine..... Many thanks to Peter (above) and his ruminations on the cave side of things #cave #epigene #hypogene #diagenesis #hyenas

A paper from my ongoing Ph.D. work has recently been published. In this paper, we highlight the process required to calculate activity diagrams to model the mineralogical changes that occur during the hydrothermal alteration of rocks. Specifically, we use the program CHNOSZ and thermodynamic database Thermoddem to understand how ultramafic rocks are altered in orogenic gold environments, compared to the alteration mineralogy observed at the Kerr-Addison deposit. We also show that even the slightly differing chemistry of komatiites versus harzburgites can lead to contrasting initial alteration assemblages. In other words, the starting composition of the host rock substantially influences what alteration minerals can be stable for a given host rock, during the formation of a gold deposit. Link to paper: https://lnkd.in/eGFWaQGH .

Explore the fascinating micro-world of a Mozambique ruby in our latest micrograph by Patthamaporn Sukkasem. Automorphous margarite crystals (CaAl2(Al2Si2O10)(OH)2) in an unheated ruby from Mozambique. The margarite crystals are surrounded by what look like healed fractures resulting from heat treatment that induced a dissolution/recristallisation mechanism. It has been suggested that these 'fractures' may be filled with margarite. Such insights are crucial in understanding gemstone characteristics and origins. 💎🔬 #GemologicalResearch #RubyAnalysis #GGTL Delve into our detailed study in the latest blog post: https://lnkd.in/dQEKkiaZ Stay informed with GGTL Laboratories for in-depth gemmological insights and discoveries. 💼🌐

An extraordinary pipefish (Teleostei, Syngnathidae) with fully developed anal fin from the Oligocene of the North Caucasus (SW Russia) A new genus and species of pipefishes (Syngnathiformes, Syngnathidae), Pshekhagnathus polypterus n. gen. n. sp. is described from the Lower Oligocene (Planorbella Beds, Lower Maikopian Series) of the North Caucasus, Russia. Unlike all the other extant and fossil syngnathids known to date, which are characterized by a very small anal fin with two to six anal-fin rays, the new pipefish described herein has a fully developed anal fin as equally almost identical to its opposite dorsal fin. This remarkable morphological feature justifies the creation of a new pipefish subfamily-Pshekhagnathinae n. subfam.-to accommodate this early Oligocene form. https://lnkd.in/dtT2FTJZ

American Mineralogist: Evidence for oceans pre-4300 Ma confirmed by preserved igneous compositions in Hadean zircon Emilia M. Cameron, Tyler B. Blum, Aaron J. Cavosie, Kouki Kitajima, Lutz Nasdala, Ian J. Orland, Chloe E. Bonamici, and John W. Valley https://lnkd.in/gR7XuF5J Cameron et al. demonstrate that primary, well-preserved domains can be recognized using standard methodologies even in zircons older than 4000 Ma. The results refute the hypothesis that mildly elevated δ18O values in Hadean zircons result from alteration. The results show that pristine domains in Jack Hills zircons that preserve primary unaltered δ18O values representative of their growth in Hadean magmas can be identified if carefully selected based on objective criteria. This study supports the conclusion that the surface of early Earth cooled and had liquid-water oceans before 4300 Ma. Thus, conditions were habitable for life 800 myr before the oldest documented microfossils. This article is part of the “Isotopes, Minerals, and Petrology: Honoring John Valley” special collection.