Goedkenite
Chemical formula: Sr₂Al(PO₄)₂(OH)
Goedkenite is a rare phosphate mineral, forming colorless, tabular crystals, discovered in granitic pegmatites in the USA.
Properties
- Mohs hardness
- 5
- Luster
- Vitreous
- Streak
- White
- Density
- 0
- Transparency
- Transparent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Identifying goedkenite in the field is practically impossible due to its small size and lack of characteristic macroscopic features. Identification requires advanced laboratory methods, such as X-ray diffraction (XRD) and chemical analysis (EDS/WDS) to confirm its composition (presence of strontium, aluminum, and phosphorus) and crystal structure. ## Distinguishing from Similar Minerals Goedkenite can be confused with many other colorless secondary minerals found in pegmatites, such as apatite, herderite, or other rare phosphates. Distinguishing it from members of its own group (e.g., arsenbrackebuschite) is only possible based on detailed chemical analysis. ## Crystal Forms Goedkenite crystals are usually very small, tabular or bladed in habit, elongated along the crystallographic axis. They often form fan-shaped or rosette-like aggregates, growing on other minerals, mainly quartz.
Geological environment
## Genesis Goedkenite is a secondary mineral, forming in the late stages of crystallization of complex granitic pegmatites. It forms as a result of hydrothermal processes that lead to the alteration of previously crystallized primary phosphate minerals, such as triphylite. Its formation is associated with the presence of strontium- and aluminum-rich solutions. ## Mineral Associations This mineral co-occurs with other phosphates typical of pegmatites. At the type locality (Palermo No. 1 Mine), it was found in association with quartz, brazilianite, siderophyllite, apatite, montebrasite, augelite, wardite, and eosphorite. ## Localities The only confirmed and well-documented occurrence of goedkenite worldwide is its type locality – the Palermo No. 1 Mine in Groton, New Hampshire, USA. This is a historic pegmatite mine known for the occurrence of many rare phosphate minerals.
Rarity
Very rare
For collectors
## Quality Criteria As a "micromount" type mineral, the collector's value of goedkenite primarily depends on the quality and size of the crystals, although these rarely exceed 1 mm. The most desirable specimens are those with sharply terminated, well-formed, transparent crystals forming aesthetic, rosette-like aggregates. Association with other rare minerals and the richness of the specimen (number of crystals on the matrix) are also important. ## Popular Localities The only source of collector specimens is the Palermo No. 1 Mine in New Hampshire, USA. Material from this locality is extremely rare and sought after by specialized collectors of systematic and "micromount" minerals.
Care and storage
## Cleaning Goedkenite specimens should be cleaned with the utmost care, using a soft brush to remove dust. Due to its rarity and potential instability, contact with water and chemical agents should be avoided. If wet cleaning is necessary, isopropyl alcohol is recommended, followed by immediate drying. ## What to Avoid Avoid contact with acids and other aggressive chemicals that can damage the mineral. It should not be heated or subjected to ultrasonication. Prolonged exposure to humidity can be harmful. ## Storage Goedkenite, as a rare mineral occurring in microscopic crystals, should be stored in specialized "micromount" boxes that protect it from mechanical damage, dust, and moisture. Storage in areas with high humidity should be avoided.