Pseudomorphism - What does it all mean?

Quite often as mineral collectors and enthusiasts we come across these terms used to describe mineral specimens. Generally they command a premium price due to thier unusual nature - However, there is a fair amount of confusion about what category a specific specimen might fit into. Let's have a look at what it all means!

 

Pseudomorphs

This is possibly the most common term encountered. Common in the carbonate family (And in most mineral groups), we often see pseudomorphs of Malachite after Azurite, or Tennantite after Azurite. These prime examples are best known from Tsumeb, in Namibia.

When naming pseudomorphs, we look at the two minerals present. In the case of the Malachite - Azurite system, the original mineral present was Azurite and the replacing mineral is Malachite. Therefore, the pseudomorph can be termed as Malachite after Azurite, or as commonly seen on mineral websites, Malachite ps. Azurite.

 

Malachite ps AzuriteMalachite ps. Azurite. Cape Minerals stock and photography.

 

Thus, we can define a pseudomorph as a mineral that has had the internal structure changed, while preserving the external form. Ie, one mineral has replaced another without a change to the crystal shape.

This is generally enough detail for mineral collectors, but we can take it one step further and define different types of pseudomorphs.

 

Substitution pseudomorphs show a slow removal of the original mineral, with a simulaneous replacement of the new mineral. Ie, as the original mineral is removed the new mineral replaces immediately. A good example of this is petrified wood - Silica replaces the wood fibres as they are removed, retaining the shape of the wood fibres. We can say that petrified wood is a substitution pseudomorph.

Another great example of this is Quartz replacing Fluorite. These specimens, although rare, are quite stunning and show the characteristics of a substitution pseudomorph beautifully. The aforementioned Malachite ps. Azurite change is a substition pseudomorph.

 

Alteration pseudomorphs are very similar to substition pseudomorphs. Indeed, alteration is often just considered as an incomplete variant of a substition psuedomorph. Put simply, the replacement has not run to completion. This is often seen with the Anglesite ps. Galena system, where an unalterered core of Galena remains.

 

Incrustation pseudomorphs, also known as epimorphs or perimorphs, occur when the "new" mineral forms a "crust" over the original mineral. The original mineral is later removed through some geochemical process. This leaves a situation whereby the replacing mineral preserves the crystal shape of the original mineral. Quartz again provides us with a fairly good example - Quartz can encrust cubes of Fluorite, which will later be dissolved.

A stunning example of this process is exhibited with Prehnite, which can overgrow calcite forming the described "crusts." At a later date the Calcite is removed, leaving Prehnite exhibiting the "crystal shape" of the original mineral, Calcite.

 

Prehnite - Calcite epimorphPrehnite - Calcite epimorph. Cape Minerals stock and photography.

 

Paramorphs can be a bit tricky to spot. These form when there is no change to the external crystal form, however a change is exhibited internally - Such as the change from Aragonite to Calcite. Note that with paramorphs the chemical composition remains the same - another great example is the Rutile - Brookite change - Both show the same chemistry (TiO2).

Simply put, we can define a paramorph as a mineral that has changed on the molecular level only. There is no change in chemical composition or external structure - Just an internal re-arrangement of molecules.

 

Generally speaking..

 

Most of the psuedomorphs you'll encounter fall into the first category, substitution psuedomorphs. Sometimes the mineral might be referred to as a partial psuedomorph - This is a reference to the described alteration psuedomorphs, which are essentially incomplete substition psuedomorphs. 

Incrustation psuedomorphs are most often simply called casts - It's up to you to decide how you would like to define the type of psuedomorph on your label! 

 

Leave your comment
Comments
2021-02-24 07:18 PM
<a href="https://lbwic.com/">IMVU Free Credits No Surveys 2021</a>
===========

Belts are a necessary supplement to append your overall look. genial in a broad array of fabrics and styles, belts provide endless opportunities to manner your fashion style. A shiny ornament is the perfect quirk to increase fun to a easy pair of jeans.

If you tend to be a bit upon the close side, get not attempt to conceal your disturb by dressing in baggy clothing. The further volume unaccompanied accentuates your size and makes you look frumpy. look for clothing that is more fitted re your waistline, but next flows away from your demean body to create more shape.

If you have patches of gray in your hair, declare using a semipermanent dye. The gray will appear to be the similar color as the perch of your hair and will last very nearly two months. even if you can't really lighten your hair in the manner of this tactic, you can choose to darken your locks if you want.

Never depart house without lotion! past you're out and about, your hands can be anxious the effects of a airing world. Regular hand-washing alone can wreak havoc on both your hands and your cuticles. Your best explanation is to always carry a small bottle of lotion in your handbag. That way, you can always put your best hand forward.

Hats are a great accessory to settle any kind of outfit. For men, there are the typical fisherman hats and baseball caps, but for women, the possibilities govern much deeper. For instance, you can wear a delectable sun hat, floppy cap or beach cap taking into account any casual dress you own.

Use a leave-in conditioner if you have upset past frizz. You desire to apply this product considering a shower, previously the hair dries. Don't be afraid to put a large amount all beyond your head, and create determined to seek both the roots and the enormously tips of the hair.

KW:
IMVU Credit Hack No Surveys
How To Get Free Credits On IMVU
IMVU Generator No Surveys
IMVU Free Credits Generator

Article sources:
1. https://www.cdc.gov/mobile/mobileapp.html
2021-02-24 10:37 PM
https://lbwic.com
===========

Belts are a critical supplement to combine your overall look. available in a broad array of fabrics and styles, belts pay for endless opportunities to way of being your fashion style. A bright co-conspirator is the absolute way to grow fun to a simple pair of jeans.
Use a leave-in conditioner if you have make miserable gone frizz. You desire to apply this product later a shower, before the hair dries. Don't be afraid to put a large amount all more than your head, and create certain to object both the roots and the unconditionally tips of the hair.

KW:
IMVU Link Generator
IMVU Free Credits No Surveys