“Clear sea water color”, this is how it appears written on the historic tag that accompanies the exceptional single crystal of beryl illustrated in the figure. Beryl - whose name, not surprisingly, derives from the Greek beryllos and means "precious blue-green sea water" - is a mineral famous for its well-known gemological varieties: emerald (green color) and aquamarine (blue color) . For this reason, the great majority of beryl crystals that have a color, transparency and clarity such as to be used in the gemological field are cut and removed from the mineralogical collections. A splendid exception is this sample, extracted in Siberia, and arrived in the Museum of Mineralogy of Sapienza with the acquisition of the Spada collection in 1852; the crystal in question is characterized by an intense blue-greenish color, by an exceptional transparency and by an excellent clarity. Only the stubborn conservation work of Monsignor Lavinio de 'Medici Spada and the successive directors of the Museum has allowed this crystal to "survive" the pressure of the jewelers and keep all its splendor intact.

Few specimens in the world are able to represent the mineral beryl as this Siberian crystal; it is sufficient to visit the showcase where it is exhibited and admire the light it releases to understand why the Latin term berillus, abbreviated to the prefix brill-, gave rise to the Italian verb “to shine”.

Vesuvius is undoubtedly one of the most fascinating mountains in the world and its name is linked to spectacular and unfortunately lethal eruptions. However, the particular geological situation is also the cause of the formation of spectacular and particular mineralogical associations which result in samples of absolute scientific value and in some cases collecting. One of the most important samples ever extracted in this locality (Monte Somma, Naples, Campania, Italy) is undoubtedly the sodalite represented here. These are white sodalite crystals in large idiomorphic crystals of

brown vesuvianite and red garnet on a rock of vesuvianite, garnet and mica. Sodalite is a silicate, part of the feldspathoids, which is normally found opaque, massive and blue in color, to the point that this mineral is commonly used as an ornamental stone for the creation of small sculptures or used in cabochon-cut jewelry. We therefore understand the importance and the exceptionality of this historical museum sample, where sodalite is found in translucent white euhedral crystals, a particular case that is found only in rare specimens from Namibia and, as in this case, from lavas of Vesuvius.

There is a class of minerals, called native elements, made up of all those minerals formed by a single element; the most famous are undoubtedly gold, silver, platinum, copper and diamond (consisting only of carbon). Yet we challenge any of these famous colleagues to beat the beauty and rarity of the sulfur samples extracted in the past in Agrigento (Sicily). Sulfur is in fact a mineral belonging to the native elements, easy to find in numerous locations on a planetary scale. Most of the times the sulfur is found in dusty masses, poorly or not crystallized at all, and is extracted and marketed almost exclusively for industrial purposes (in insecticides, fungicides, explosives, etc.). Despite being so widespread, sulfur can also be found in samples of absolute mineralogical importance, in particular this mineral "has chosen" a splendid Italian region, Sicily, as a location to manifest itself in its most aesthetic specimens. Samples like this one illustrated in the photograph, with crystals characterized by an intense yellow color, excellent transparency, perfect prismatic dress and considerable size, are absolutely among the most desired and sought after in the mineralogical panorama. Acquired in 1852 by the Museum of Mineralogy, within the Spada Collection, this sample enriches, together with numerous other specimens in the Museum, the most important collection in the world of Sicilian sulfur specimens. To increase the value and prestige of minerals like this is the fact that the Sicilian sulfur mines are no longer exploited and it is therefore not possible to extract new specimens nowadays: the sulfur present in the mineralogical collection of Sapienza is the classic case of museum sample in which the aesthetic beauty is equal to the historical value.

An exceptional gem-quality imperial topaz crystal, reddish-orange in color, weighing 286.6 grams, has been in the collection of the Museum of Mineralogy for over 150 years.

The sample comes from the Ouro Preto area (Minas Gerais, Brazil); this area is currently the only one in the world from which imperial topaz of a color and clarity such as to make it usable also in the gemological field is extracted.

The term "imperial" associated with topaz is used exclusively for crystals that have varying colors from yellow-orange, to orange-pink, orange-reddish, to red, to purple; nowadays it has become almost impossible to extract samples of exceptional quality and large dimensions; in the very rare cases in which this happens, imperial topaz crystals reach astronomical market prices and are almost always cut to be used in high jewelery.

These factors contribute to making the imperial topaz of the Museum of Mineralogy of Sapienza even more extraordinary: this crystal, which has remained intact for decades and preserved from the cut, came into the collection at a time when the best pieces still reached important institutions. museum - unlike today, where the best samples are the prerogative of wealthy private collectors -, according to many experts, represents the best example of imperial topaz in the world.

This splendid example of Sicilian amber (also called simetite or more improperly succinite) is one of the points of pride of the Spada collection and more generally of the Museum of Mineralogy. Sicilian amber associates with a high aesthetic and gemological value - for the transparency and richness of the colors - an exceptional historical importance, to the point of making it one of the most appreciated and desired gems. The most abundant finds of this variety of amber occurred in a time interval between the first half of 1600 and the beginning of 1970. The simethite deposits have never been located, in fact, starting from the primary deposits located inland Sicilian, amber was removed during intense rainy events that caused landslides and disruptions; on these occasions the erosive action of the water detached pieces of different sizes from their natural location and dispersed them in the nearby countryside or in waterways and from these to the sea where they were found beached around Catania and on the southern coast of Sicily. The reason why we no longer have news about the discovery of amber samples after the 1970s is still unknown, but it could be attributed to the anthropic impact on the territory that has changed the talweg of the waterways that regulated the transport of this material, due to the construction of dams and dams. In conclusion, today Sicilian amber is no longer extracted and a sample like this, which entered in 1852 to enrich the collection of the current Museum of Mineralogy, represents an important testimony of Italian mineralogy and gemology.

The meteorite collection of the Museum of Mineralogy, built over more than 200 years of acquisitions and donations, is one of the most important internationally.

Among the pieces of greater historical importance, this meteorite of 52 g stands out, which fell at 1 pm on April 26, 1803 at L'Aigle (Orne, France), acquired by the Museum in 1852.

The exceptional nature of the L'Aigle meteorite is due to the fact that it is considered a watershed in the history of meteorites: before this fall there were the most disparate theories on the origin of meteorites (products deriving from distant volcanic eruptions, transported desert rocks from the wind etc.); was the scholar E. Chladni,

considered the founding father of meteoritics who, observing the fall of L'Aigle, formulated the correct theory that meteorites came from extraterrestrial bodies, mainly based on the statements of many witnesses who observed "a shower of stones thrown by a meteor".

The fragments of this meteorite, an ordinary type L6 chondrite, all belong to historical collections or important private collections; it is practically impossible nowadays to meet someone willing to deprive themselves of it, both with changes and with sales, so there are very few institutions that can boast the possession of a meteorite of such importance and the honor of being able to exhibit it for the benefit of visitors. For meteorite enthusiasts, observing a fragment of L'Aigle live is like being in front of Leonardo Da Vinci's Mona Lisa.

One of the most important samples in the Spada Collection, which entered the Museum of Mineralogy in 1852, is represented by this garnet from Testa Ciarva, Mussa, Val d'Ala Lanzo, Turin, Piedmont, Italy. Garnets are a family of minerals that are very widespread on a planetary scale and are found in a very wide range of colors and qualities; However, there are some extraction places where garnets take on particular and unique connotations, if we associate this with the fact that some deposits have become unproductive or restricted by excavation prohibitions, here some samples, extracted many decades ago can take on a particular value scientific, historical and aesthetic. This is the case of the Val d'Ala garnets, with transparency and luster to make them of gem quality, in association with diopside crystals. In particular, the locality “Testa Ciarva” (“Calva” in the local dialect), has become famous both for the quality and quantity of the samples supplied over the years. This field was certainly the most exploited in the valley, even with the abundant use of explosives. Today, due to this, the area has been totally closed to the search and collection of minerals. This adds greater value to the specimens present in the mineralogical collections. The minerals that have made the place famous the most are garnet and diopside, both present in the sample inherited from the Spada Collection: the garnet crystals are of extraordinary elegance, of an intense red-hyacinth-deep color, with a habit usually given from the combination of the icositetrahedron and the rhombododecahedron; the diopside crystals are gray-green in color and characterize this particular and exclusive association of this locality. The garnets of Val d'Ala, thanks to their rarity, their history and their beauty, are absolutely among the most famous and admired mineralogical specimens on a world scale.

A highlight of the meteorite collection of the Museum of Mineralogy is undoubtedly this 38.1 g fragment of the Renazzo meteorite. At 8.30 pm on January 15, 1824 fragments of a meteorite, weighing about 10 kg, fell near the town of Renazzo, in the province of Ferrara. It is said that this meteorite broke into 3-4 main fragments, because a woman at the time of the fall said she heard a triple noise. The people of Renazzo were frightened by noises, such as cannon shots, and wondered where they could come from since the sky was clear that evening.

A few years later some specimens of this meteorite were donated, within the Spada collection, to the Museum of Mineralogy which still preserves them and exhibits them to the public.

The importance of this fall is that this meteorite, at the time it was discovered, represented a unicum in the meteorite panorama, to the point that it became the progenitor of a group of carbonaceous meteorites (discovered later) called precisely CR (the R sta for Renazzo). Renazzo is therefore one of the meteorites of greater historical and significant importance for meteoritics. Due to its importance it is one of the most desired meteorites by collectors and enthusiasts which, given the rarity and inalienability of many collections, is often destined to remain an object of desire and to be observed exclusively in publicly accessible collections. Given its uniqueness, the Renazzo meteorite has received various international "awards": in 1962 Mason and Wiik published the historic article "The Renazzo Meteorite" - where they detect the uniqueness of the Italian meteorite - in the American Museum Novitates of the Mineralogy Department of American Museum of Natural History in New York; in 1964 the article "Rare Gases in the Chondrite Renazzo" by Reynolds and Turner, of the University of California, appears; in 2000 the article 'Star dust' by Russell and Alexander was published in the prestigious periodical New Scientist, indirectly dedicated to Renazzo, where it speaks of "diamonds forged inside long-extinct stars (giants red) that are providing us with important information on our origins ”, in particular an unusual abundance of diamonds is discovered in Renazzo, identified so far with the same high values only in the Leoville meteorite.

On May 8, 1846, at 9.15 in the morning, a meteorite fell near Tolentino, a small town in the province of Macerata (Marche). It was the famous mineralist Giovanni Strüver, who was later called by Quintino Sella to direct the Museum of Mineralogy in Rome, who discovered this important Italian meteorite. The main mass was subsequently purchased, in 1846, and used for the description, by Monsignor Lavinio de 'Medici Spada. Having studied this meteorite, later called Monte Milone in honor of the place where it was found (a small town of six thousand inhabitants now called Pollenza), was a source of pride in the life of this great man of letters and humanists. The meteorite of Monte Milone, weighing 2044 grams, represents one of the most sensational specimens of the collection of minerals that Spada managed to put together and which, purchased in 1852 by the papal government for the University of Rome, still forms an important nucleus today. of this Mineralogy Museum.

Monte Milone is an ordinary L5-type chondrite and its estimated total mass is about 3 Kg; for this reason, the specimen illustrated in the photo weighing over 2 kg, on permanent display at the Museum of Mineralogy, represents the main mass of one of the most important meteorites that have fallen in Italy. To historical and scientific importance, this sample combines an aesthetic beauty given by the perfect state of conservation and the clear melting crust that testifies to the passage of this meteorite in the earth's atmosphere.

The word "diamond" derives from the Latin name adamas (genitive adamantis), which means "indomitable" and refers to the exceptional hardness of this stone. Diamond is a mineral made up of carbon (C) for 99.95% and other trace elements for the remaining percentage.

It has a density of 3.52 and its hardness (resistance that a mineral opposes to scratching) is equal to 10, which is the maximum hardness of the Mohs scale (scale used for evaluating the hardness of materials); the very high refractive index is 2.42. The diamond also has the highest luster term for transparent minerals, which is referred to as adamantine.

These cold but characteristic properties can be used to characterize the diamond, but they are not enough to describe this splendid and clear 1.59 carat crystal, extracted in Brazil,

preserved by the cut and donated to the Museum of Mineralogy by Monsignor Lavinio de 'Medici Spada. Diamonds like these are nowadays impossible to find, as the rarity in the discovery of crystals of size and quality such as those that characterize the specimen illustrated here, joins the rarity due to the fact that crystals with these characteristics are cut and used in jewelry store.

This diamond, deposited in 1852, is only one of the first among those present in the Museum of Mineralogy, which also houses a splendid iridescent diamond inside the Dactyliotheca and several specimens of ancient diamonds including a historical sample on a matrix from the Kimberley mine. (purchased by the museum on March 5, 1887 for a value of 600 marks, or 750 lire). In the museum there is also a collection of reproductions of famous diamonds.

Axinite or assinite, as reported on the original tag, brown in large crystals with albite and epidote on green schist, from St. Cristophe en Oisans, Isere, France.

Axinite is part of a group of borosilicates characterized by the presence of Ca and Al, has pyroelectric and piezoelectric properties and is very difficult to meet in samples of good quality and size due to its rarity and the difficulty of extraction and storage. (due to the fragility of the crystals). The specimen of axinite described here, which arrived in the Museum of Mineralogy in the Spada collection in 1852, is a splendid exception.

The sample has an absolute aesthetic value, where the axinite crystals, from transparent to translucent, are characterized by a perfect triclinic dress (one of the rarest in nature) and by an attractive brown color that turns to violet due to a strong pleochroism visible to the naked eye (properties of some minerals, which show different colors depending on the orientation of the crystal). To increase the importance of the sample illustrated in the figure is its origin: this example comes from excavations carried out in the nineteenth century in St Christophe-en-Oisans, a famous type locality for axinite, where the deposits are currently exhausted. The essence of the museum is therefore splendidly concentrated in this axinite: 1) the historical importance that translates into observing minerals that can no longer be extracted, 2) being able to enjoy the most beautiful pieces among those still around, coming from mines exhausted.

The original tag still shows the term mesitite, a disused synonym to indicate magnesite, the famous magnesium carbonate, but still valid to indicate samples with high iron content (for some this term indicates a variety of magnesite rich in iron). The splendid specimen illustrated in the figure comes from the well-known type deposits of Traversella, Ivrea, Piedmont, Italy, and consists of large lenticular crystals of iron-rich magnesite, grouped with crystallized hyaline quartz on white dolomite, with partial patina of ocher limonite and micaceous hematite .

One of the prides of the Sapienza Museum of Mineralogy is that it possesses one of the largest and richest collections in the world of samples extracted in Italy, often coming from mines that are now exhausted or inaccessible; this collection was made possible thanks to large acquisitions and donations which took place, as highlighted in this volume, in the pre-unification period of Italy.

This magnesite, purchased in 1852 by Monsignor Lavinio de 'Medici Spada, constitutes for its historical-scientific importance, and for its beauty, a backbone of this extraordinary collection of Italian minerals.

The Dactyliotheca is a collection of 388 precious and ornamental stones, often mounted on sheets of agate or other ornamental material, especially with an octagonal composite cut, ranging from 28x18x2 to 40x20x3 mm, or with an oval cabochon cut of 20x15x4 mm. . These foils can be interchangeable on two rings, which are also included in the collection. The gems, of different shapes and cuts, are frequently surmounted by small gems or by insects built with various materials.

The stones are arranged on 12 plateaux, divided into three sections of four plateaux each according to the shape and type. The plateaux can be placed one on top of the other in a wooden cabinet or in three book-shaped containers, bound in red leather, with the inscription Lang's Museum Mineralogicum (Inventory of the University of Rome No 402). Nowadays the Dactyliotheca represents one of the most important collections of gems in the world to the point that it was exhibited at the two main world events in the sector: the special exhibition in Munich (1996) and that of Tucson (Arizona , USA) in 2006.

A detailed study of the Dactyliotheca was published by: Graziani G., (1996) "Periodico di Mineralogia", Rome (1996), 65, 79-204