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Phosphosiderite Properties Facts and Photos

phosphosiderite mineral sphere

What is Phosphosiderite?

Phosphosiderite is a relatively rare mineral first discovered in 1858.  It was named in 1890 after its main constituents which are phosphate and iron.

The name phosphosiderite comes from 'phospho' (from phosphate) and 'siderite' from the Latin 'sídēros' meaning 'iron'.

This naturally occurring form of iron phosphate can only be found in a handful of locations worldwide.  Most phosphosiderite comes from Germany, USA, Portugal, Chile and Argentina.

Although once known as metastrengite this name is now mostly obsolete.

Crystals of phosphosiderite occur in shades of red and pink and tend to be extremely small.  This mineral occurs more widely with a massive or botryoidal crystal habit.  This stone is mainly used for lapidary purposes.

In mineralogy the term crystal habit describes the external shape of a crystal or group of crystals and how well it/they have formed.  The habit described as massive means the mineral's crystals grow tightly together as one large mass.  Unlike individual well-formed crystals they have no visible internal structure and no distinguishable external shape.

An good example of a mineral whose crystals occur in this way is turquoise. the mineral turquoise embedded in rock matrix

The crystal habit described as botryoidal means crystals have a rounded shape.  The word comes from the Ancient Greek word 'botrys' meaning 'bunch of grapes'. malachite with a botryoidal crystal habit

Phosphosiderite that occurs in massive form can be found in striking shades of lilac, lavender and purple.  Most of this stone is used to produce cabochons.

Phosphosiderite can feature yellow spidery veins which are inclusions of cacoxenite (ka~cox~enite).  This iron aluminium phosphate mineral usually but not always occurs within other minerals.
phosphosiderite tumbled stones
On Mohs scale of mineral hardness phosphosiderite grades 3.5 to 4 which means it's quite soft.  It's also brittle so must be handled carefully.

Article Pictures

The picture of the mineral turquoise in rock matrix is courtesy of Stan Celestian.  The malachite with a botryoidal crystal habit is courtesy of Ron Wolf.  The phosphosiderite tumbled stones are from our collection.

All pictures are clickable and redirect to the original non-compressed image.   

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